From 432900f73f1660c6fa9c25b90f3c8f2939b749f6 Mon Sep 17 00:00:00 2001
From: Renae Metcalf <kmetcalf@cert.org>
Date: Tue, 4 Nov 2025 14:44:39 -0500
Subject: [PATCH 01/17] Remove user-defined function ability and member access

---
 src/evaluate.js | 30 +-----------------------------
 1 file changed, 1 insertion(+), 29 deletions(-)

diff --git a/src/evaluate.js b/src/evaluate.js
index f23cef7e..af15b521 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -1,4 +1,4 @@
-import { INUMBER, IOP1, IOP2, IOP3, IVAR, IVARNAME, IFUNCALL, IFUNDEF, IEXPR, IEXPREVAL, IMEMBER, IENDSTATEMENT, IARRAY } from './instruction';
+import { INUMBER, IOP1, IOP2, IOP3, IVAR, IVARNAME, IFUNCALL, IEXPR, IEXPREVAL, IENDSTATEMENT, IARRAY } from './instruction';
 
 export default function evaluate(tokens, expr, values) {
   var nstack = [];
@@ -72,38 +72,10 @@ export default function evaluate(tokens, expr, values) {
       } else {
         throw new Error(f + ' is not a function');
       }
-    } else if (type === IFUNDEF) {
-      // Create closure to keep references to arguments and expression
-      nstack.push((function () {
-        var n2 = nstack.pop();
-        var args = [];
-        var argCount = item.value;
-        while (argCount-- > 0) {
-          args.unshift(nstack.pop());
-        }
-        var n1 = nstack.pop();
-        var f = function () {
-          var scope = Object.assign({}, values);
-          for (var i = 0, len = args.length; i < len; i++) {
-            scope[args[i]] = arguments[i];
-          }
-          return evaluate(n2, expr, scope);
-        };
-        // f.name = n1
-        Object.defineProperty(f, 'name', {
-          value: n1,
-          writable: false
-        });
-        values[n1] = f;
-        return f;
-      })());
     } else if (type === IEXPR) {
       nstack.push(createExpressionEvaluator(item, expr, values));
     } else if (type === IEXPREVAL) {
       nstack.push(item);
-    } else if (type === IMEMBER) {
-      n1 = nstack.pop();
-      nstack.push(n1[item.value]);
     } else if (type === IENDSTATEMENT) {
       nstack.pop();
     } else if (type === IARRAY) {

From 146ff83a4fe31b8bf91bd74d54889405a5a23c49 Mon Sep 17 00:00:00 2001
From: Renae Metcalf <kmetcalf@cert.org>
Date: Tue, 4 Nov 2025 14:48:01 -0500
Subject: [PATCH 02/17] restrict functions to ./functions.js

---
 src/evaluate.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/evaluate.js b/src/evaluate.js
index af15b521..caf6250f 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -67,6 +67,16 @@ export default function evaluate(tokens, expr, values) {
         args.unshift(resolveExpression(nstack.pop(), values));
       }
       f = nstack.pop();
+			var isAllowedFunc = false;
+			for (var key in expr.functions) {
+				if (expr.functions[key] === f) {
+					isAllowedFunction = true;
+					break;
+				}
+			}
+			if (!isAllowedFunc) {
+				throw new Error('Is not an allowed function.')
+			}
       if (f.apply && f.call) {
         nstack.push(f.apply(undefined, args));
       } else {

From 955f390dd395f51ecef7a12ae382042a3dac5b45 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:00:00 -0500
Subject: [PATCH 03/17] Updated 2.0.3 for secure expr-eval

---
 src/evaluate.js   | 85 +++++++++++++++++++++++++++++++++++++++--------
 test/operators.js |  8 ++---
 test/parser.js    |  2 +-
 test/security.js  | 68 +++++++++++++++++++++++++++++++++++++
 4 files changed, 145 insertions(+), 18 deletions(-)
 create mode 100644 test/security.js

diff --git a/src/evaluate.js b/src/evaluate.js
index caf6250f..f9aa992e 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -1,4 +1,4 @@
-import { INUMBER, IOP1, IOP2, IOP3, IVAR, IVARNAME, IFUNCALL, IEXPR, IEXPREVAL, IENDSTATEMENT, IARRAY } from './instruction';
+import { INUMBER, IOP1, IOP2, IOP3, IVAR, IVARNAME, IFUNCALL, IFUNDEF, IEXPR, IEXPREVAL, IMEMBER, IENDSTATEMENT, IARRAY } from './instruction';
 
 export default function evaluate(tokens, expr, values) {
   var nstack = [];
@@ -9,6 +9,30 @@ export default function evaluate(tokens, expr, values) {
     return resolveExpression(tokens, values);
   }
 
+  /**
+   * Checks if a function reference 'f' is explicitly allowed to be executed.
+   * This logic is the core security allowance gate.
+   */
+  var isAllowedFunc = function (f) {
+      if (typeof f !== 'function') return true;
+
+      for (var key in expr.functions) {
+          if (expr.functions[key] === f) return true;
+      }
+
+      if (f.__expr_eval_safe_def) return true;
+
+      for (var key in values) {
+          if (typeof values[key] === 'object' && values[key] !== null) {
+              for (var subKey in values[key]) {
+                  if (values[key][subKey] === f) return true;
+              }
+          }
+      }
+      return false;
+  };
+  /* --- END: LOCAL HELPER FUNCTION FOR SECURITY --- */
+
   var numTokens = tokens.length;
 
   for (var i = 0; i < numTokens; i++) {
@@ -50,7 +74,11 @@ export default function evaluate(tokens, expr, values) {
         nstack.push(expr.unaryOps[item.value]);
       } else {
         var v = values[item.value];
-        if (v !== undefined) {
+          if (v !== undefined) {
+              if (typeof v === 'function' && !isAllowedFunc(v)) {
+                /* function is not registered, not marked safe, and not a member function. BLOCKED. */
+                throw new Error('Variable references an unallowed function: ' + item.value);
+            }
           nstack.push(v);
         } else {
           throw new Error('undefined variable: ' + item.value);
@@ -66,26 +94,57 @@ export default function evaluate(tokens, expr, values) {
       while (argCount-- > 0) {
         args.unshift(resolveExpression(nstack.pop(), values));
       }
-      f = nstack.pop();
-			var isAllowedFunc = false;
-			for (var key in expr.functions) {
-				if (expr.functions[key] === f) {
-					isAllowedFunction = true;
-					break;
-				}
-			}
-			if (!isAllowedFunc) {
-				throw new Error('Is not an allowed function.')
-			}
+	f = nstack.pop();
+
+      // --- FINAL SECURITY CHECK ---
+      if (!isAllowedFunc(f)) {
+          throw new Error('Is not an allowed function.');
+      }
+      // --- END FINAL SECURITY CHECK ---
+
       if (f.apply && f.call) {
         nstack.push(f.apply(undefined, args));
       } else {
         throw new Error(f + ' is not a function');
       }
+    } else if (type === IFUNDEF) {
+      // Create closure to keep references to arguments and expression
+      nstack.push((function () {
+        var n2 = nstack.pop();
+        var args = [];
+        var argCount = item.value;
+        while (argCount-- > 0) {
+          args.unshift(nstack.pop());
+        }
+        var n1 = nstack.pop();
+        var f = function () {
+          var scope = Object.assign({}, values);
+          for (var i = 0, len = args.length; i < len; i++) {
+            scope[args[i]] = arguments[i];
+          }
+          return evaluate(n2, expr, scope);
+        };
+        // f.name = n1
+        Object.defineProperty(f, 'name', {
+          value: n1,
+          writable: false
+        });
+        // *** MARK AS SAFE FOR SECURITY CHECK ***
+        Object.defineProperty(f, '__expr_eval_safe_def', {
+            value: true,
+            writable: false
+        });
+        // ***************************************
+        values[n1] = f;
+        return f;
+      })());
     } else if (type === IEXPR) {
       nstack.push(createExpressionEvaluator(item, expr, values));
     } else if (type === IEXPREVAL) {
       nstack.push(item);
+    } else if (type === IMEMBER) {
+      n1 = nstack.pop();
+      nstack.push(n1[item.value]);
     } else if (type === IENDSTATEMENT) {
       nstack.pop();
     } else if (type === IARRAY) {
diff --git a/test/operators.js b/test/operators.js
index 07d15aa5..d6656983 100644
--- a/test/operators.js
+++ b/test/operators.js
@@ -162,17 +162,17 @@ describe('Operators', function () {
       assert.strictEqual(Parser.evaluate('1 and 1 and 0'), false);
     });
 
-    it('skips rhs when lhs is false', function () {
+    it('skips rhs when lhs is false for AND operator', function () {
       var notCalled = spy(returnFalse);
 
       assert.strictEqual(Parser.evaluate('false and notCalled()', { notCalled: notCalled }), false);
       assert.strictEqual(notCalled.called, false);
     });
 
-    it('evaluates rhs when lhs is true', function () {
+    it('evaluates rhs when lhs is true for AND operator', function () {
       var called = spy(returnFalse);
 
-      assert.strictEqual(Parser.evaluate('true and called()', { called: called }), false);
+	assert.strictEqual(Parser.evaluate('true and spies.called()', { spies: {called: called }}), false);
       assert.strictEqual(called.called, true);
     });
   });
@@ -212,7 +212,7 @@ describe('Operators', function () {
     it('evaluates rhs when lhs is false', function () {
       var called = spy(returnTrue);
 
-      assert.strictEqual(Parser.evaluate('false or called()', { called: called }), true);
+	assert.strictEqual(Parser.evaluate('false or spies.called()', { spies: {called: called }}), true);
       assert.strictEqual(called.called, true);
     });
   });
diff --git a/test/parser.js b/test/parser.js
index bf4459d2..c0d1bdc7 100644
--- a/test/parser.js
+++ b/test/parser.js
@@ -234,7 +234,7 @@ describe('Parser', function () {
         assert.strictEqual(parser.parse('sin;').toString(), '(sin)');
         assert.strictEqual(parser.parse('(sin)').toString(), 'sin');
         assert.strictEqual(parser.parse('sin; (2)^3').toString(), '(sin;(2 ^ 3))');
-        assert.deepStrictEqual(parser.parse('f(sin, sqrt)').evaluate({ f: function (a, b) { return [ a, b ]; }}), [ Math.sin, Math.sqrt ]);
+/*         assert.deepStrictEqual(parser.parse('f(sin, sqrt)').evaluate({ f: function (a, b) { return [ a, b ]; }}), [ Math.sin, Math.sqrt ]); */
         assert.strictEqual(parser.parse('sin').evaluate(), Math.sin);
         assert.strictEqual(parser.parse('cos;').evaluate(), Math.cos);
         assert.strictEqual(parser.parse('cos;tan').evaluate(), Math.tan);
diff --git a/test/security.js b/test/security.js
new file mode 100644
index 00000000..1ebd573b
--- /dev/null
+++ b/test/security.js
@@ -0,0 +1,68 @@
+'use strict';
+var assert = require('assert');
+var Parser = require('../dist/bundle').Parser;
+var fs = require('fs');
+var child_process = require('child_process');
+
+// 1. Setup the Dangerous Context
+var context = {
+    write: (path, data) => fs.writeFileSync(path, data),
+    exec: (cmd) => console.log('Executing:', cmd)
+};
+
+// --- Test Case 1: Direct Call to a Dangerous Global/Context Function ---
+it('should fail on direct function call to an unallowed function', function () {
+    var parser = new Parser();
+
+    // The evaluator should throw an error because 'write' is not an allowed function
+    assert.throws(() => {
+        parser.evaluate('write("pwned.txt","Hello!")', context);
+    }, Error);
+});
+
+// --- Test Case 2: Function Definition (IFUNDEF) should still be safe ---
+it('should allow IFUNDEF but keep function calls safe', function () {
+    // Enable IFUNDEF
+    var parserWithFndef = new Parser({
+        operators: { fndef: true }
+    });
+    
+    // Expression: define an expression-internal function 'g' and call it.
+    // 'g' itself is safe because it only uses safe operators.
+    var safeExpr = '(f(x) = x * x)(5)';
+
+    assert.equal(parserWithFndef.evaluate(safeExpr), 25, 
+    		 'Should correctly evaluate an expression with an allowed IFUNDEF.');
+
+    // Expression: Define a function 'h' that calls the *unallowed* function 'write'
+    var dangerousExpr = '((h(x) = write("pwned.txt", x)) + h(5))';
+    
+    // The call to 'write' inside the expression-defined function 'h' should still fail
+    assert.throws(() => {
+        parserWithFndef.evaluate(dangerousExpr, context);
+    }, Error);
+});
+
+// --- Test Case 3: Variable Assignment to a Dangerous Function ---
+it('should fail when a variable is assigned a dangerous function', function () {
+    var parser = new Parser();
+    
+    // The variable 'evil' points to the 'exec' function from the context
+    var dangerousContext = { ...context, evil: context.exec };
+    
+    // The evaluator should throw an error because 'evil' is a variable, 
+    // but the final call attempts to execute a function that is not in expr.functions.
+    assert.throws(() => {
+        parser.evaluate('evil("ls -lh /")', dangerousContext);
+    }, Error);
+});
+
+it('PoC provided by researcher VU#263614 deny child exec process', function() { 
+    var parser = new Parser();
+    var context = {
+	exec: child_process.execSync
+    };
+    assert.throws(() => {
+	parser.evaluate('exec("whoami")', context);
+    }, Error);
+});

From 084b27cbef138ecffee0bf4069e7d779a247cd96 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:09:04 -0500
Subject: [PATCH 04/17] Update the parser tests with parser.functions

---
 test/parser.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/parser.js b/test/parser.js
index c0d1bdc7..1a3c1511 100644
--- a/test/parser.js
+++ b/test/parser.js
@@ -234,7 +234,7 @@ describe('Parser', function () {
         assert.strictEqual(parser.parse('sin;').toString(), '(sin)');
         assert.strictEqual(parser.parse('(sin)').toString(), 'sin');
         assert.strictEqual(parser.parse('sin; (2)^3').toString(), '(sin;(2 ^ 3))');
-/*         assert.deepStrictEqual(parser.parse('f(sin, sqrt)').evaluate({ f: function (a, b) { return [ a, b ]; }}), [ Math.sin, Math.sqrt ]); */
+        assert.deepStrictEqual((function() { parser.functions.f = function (a, b) { return [ a, b ]; }; return parser.parse('f(sin, sqrt)').evaluate();})(), [ Math.sin, Math.sqrt ]);
         assert.strictEqual(parser.parse('sin').evaluate(), Math.sin);
         assert.strictEqual(parser.parse('cos;').evaluate(), Math.cos);
         assert.strictEqual(parser.parse('cos;tan').evaluate(), Math.tan);

From 0cf073c21237b7e7cd5d371a382f8f7011e3fcd8 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:15:21 -0500
Subject: [PATCH 05/17] Updates to security.js

---
 test/security.js | 37 +++++++++----------------------------
 1 file changed, 9 insertions(+), 28 deletions(-)

diff --git a/test/security.js b/test/security.js
index 1ebd573b..d688d488 100644
--- a/test/security.js
+++ b/test/security.js
@@ -4,64 +4,45 @@ var Parser = require('../dist/bundle').Parser;
 var fs = require('fs');
 var child_process = require('child_process');
 
-// 1. Setup the Dangerous Context
+/* A context of potential dangerous stuff */
 var context = {
     write: (path, data) => fs.writeFileSync(path, data),
-    exec: (cmd) => console.log('Executing:', cmd)
+    cmd: (cmd) => console.log('Executing:', cmd),
+    exec: child_process.execSync
 };
 
-// --- Test Case 1: Direct Call to a Dangerous Global/Context Function ---
 it('should fail on direct function call to an unallowed function', function () {
     var parser = new Parser();
-
-    // The evaluator should throw an error because 'write' is not an allowed function
     assert.throws(() => {
         parser.evaluate('write("pwned.txt","Hello!")', context);
     }, Error);
 });
 
-// --- Test Case 2: Function Definition (IFUNDEF) should still be safe ---
 it('should allow IFUNDEF but keep function calls safe', function () {
-    // Enable IFUNDEF
     var parserWithFndef = new Parser({
         operators: { fndef: true }
     });
-    
-    // Expression: define an expression-internal function 'g' and call it.
-    // 'g' itself is safe because it only uses safe operators.
     var safeExpr = '(f(x) = x * x)(5)';
-
-    assert.equal(parserWithFndef.evaluate(safeExpr), 25, 
-    		 'Should correctly evaluate an expression with an allowed IFUNDEF.');
-
-    // Expression: Define a function 'h' that calls the *unallowed* function 'write'
+    assert.equal(parserWithFndef.evaluate(safeExpr), 25,
+		 'Should correctly evaluate an expression with an allowed IFUNDEF.');
     var dangerousExpr = '((h(x) = write("pwned.txt", x)) + h(5))';
-    
-    // The call to 'write' inside the expression-defined function 'h' should still fail
     assert.throws(() => {
         parserWithFndef.evaluate(dangerousExpr, context);
     }, Error);
 });
 
-// --- Test Case 3: Variable Assignment to a Dangerous Function ---
 it('should fail when a variable is assigned a dangerous function', function () {
     var parser = new Parser();
-    
-    // The variable 'evil' points to the 'exec' function from the context
-    var dangerousContext = { ...context, evil: context.exec };
-    
-    // The evaluator should throw an error because 'evil' is a variable, 
-    // but the final call attempts to execute a function that is not in expr.functions.
+
+    var dangerousContext = { ...context, evil: context.cmd };
+
     assert.throws(() => {
         parser.evaluate('evil("ls -lh /")', dangerousContext);
     }, Error);
 });
 
-it('PoC provided by researcher VU#263614 deny child exec process', function() { 
+it('PoC provided by researcher VU#263614 deny child exec process', function() {
     var parser = new Parser();
-    var context = {
-	exec: child_process.execSync
-    };
     assert.throws(() => {
 	parser.evaluate('exec("whoami")', context);
     }, Error);

From ae20d0a59fce5b82ec97da641ca9da528f70e55f Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:16:25 -0500
Subject: [PATCH 06/17] Updated expr-eval package

---
 package.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index 36260e00..1dc5ca19 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "expr-eval",
-  "version": "2.0.2",
-  "description": "Mathematical expression evaluator",
+  "version": "2.0.3",
+  "description": "Mathematical expression evaluator with security",
   "main": "dist/bundle.js",
   "module": "dist/index.mjs",
   "typings": "parser.d.ts",

From 6a2bd624ace8a515a5459bd48f52d63a3c9776e9 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:34:25 -0500
Subject: [PATCH 07/17] npm updates were run

---
 package.json | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/package.json b/package.json
index 1dc5ca19..48177249 100644
--- a/package.json
+++ b/package.json
@@ -10,17 +10,17 @@
   },
   "dependencies": {},
   "devDependencies": {
-    "eslint": "^6.3.0",
-    "eslint-config-semistandard": "^15.0.0",
-    "eslint-config-standard": "^13.0.1",
-    "eslint-plugin-import": "^2.15.0",
-    "eslint-plugin-node": "^9.2.0",
-    "eslint-plugin-promise": "^4.0.1",
-    "eslint-plugin-standard": "^4.0.0",
-    "mocha": "^6.2.0",
-    "nyc": "^14.1.1",
-    "rollup": "^1.20.3",
-    "rollup-plugin-uglify": "^6.0.3"
+    "eslint": "^9.39.1",
+    "eslint-config-semistandard": "^17.0.0",
+    "eslint-config-standard": "^17.1.0",
+    "eslint-plugin-import": "^2.32.0",
+    "eslint-plugin-node": "^11.1.0",
+    "eslint-plugin-promise": "^7.2.1",
+    "eslint-plugin-standard": "^5.0.0",
+    "mocha": "^11.7.4",
+    "nyc": "^17.1.0",
+    "rollup": "^4.52.5",
+    "rollup-plugin-uglify": "^6.0.4"
   },
   "scripts": {
     "test": "npm run build && mocha",

From 1af79833e89a6f60b7ab0ce4893b1250d75e3c3e Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 4 Nov 2025 18:58:14 -0500
Subject: [PATCH 08/17] Updates devDependencies

---
 package.json         |  7 +++----
 rollup-esm.config.js | 22 +++++++++++++++++-----
 rollup-min.config.js | 24 +++++++++++++++++++-----
 rollup.config.js     |  3 ++-
 4 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/package.json b/package.json
index 48177249..215f00ba 100644
--- a/package.json
+++ b/package.json
@@ -8,19 +8,18 @@
   "directories": {
     "test": "test"
   },
-  "dependencies": {},
   "devDependencies": {
-    "eslint": "^9.39.1",
+    "eslint": "^8.57.0",
     "eslint-config-semistandard": "^17.0.0",
     "eslint-config-standard": "^17.1.0",
     "eslint-plugin-import": "^2.32.0",
     "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-promise": "^7.2.1",
+    "eslint-plugin-promise": "^6.0.0",
     "eslint-plugin-standard": "^5.0.0",
     "mocha": "^11.7.4",
     "nyc": "^17.1.0",
     "rollup": "^4.52.5",
-    "rollup-plugin-uglify": "^6.0.4"
+    "@rollup/plugin-terser": "^0.4.4"
   },
   "scripts": {
     "test": "npm run build && mocha",
diff --git a/rollup-esm.config.js b/rollup-esm.config.js
index d530a43f..d4b84db2 100644
--- a/rollup-esm.config.js
+++ b/rollup-esm.config.js
@@ -1,7 +1,19 @@
-import rollupConfig from './rollup.config';
+// rollup-esm.config.js (Converted to CommonJS)
 
-rollupConfig.plugins = [];
-rollupConfig.output.file = 'dist/index.mjs';
-rollupConfig.output.format = 'esm';
+// 1. Use require() to import the base config
+const rollupConfig = require('./rollup.config.js');
 
-export default rollupConfig;
+// Create a copy of the base configuration object to avoid modifying it
+// This is critical since 'rollupConfig' is a shared object.
+const esmConfig = { ...rollupConfig };
+
+// 2. Apply ESM-specific changes to the copied object
+esmConfig.plugins = []; // No minification for the base ESM file
+esmConfig.output = {
+    ...rollupConfig.output,
+    file: 'dist/index.mjs',
+    format: 'esm'
+};
+
+// 3. Use module.exports to export the configuration
+module.exports = esmConfig;
diff --git a/rollup-min.config.js b/rollup-min.config.js
index 222fafa3..fb397603 100644
--- a/rollup-min.config.js
+++ b/rollup-min.config.js
@@ -1,7 +1,21 @@
-import rollupConfig from './rollup.config';
-import { uglify } from 'rollup-plugin-uglify';
+// rollup-min.config.js (Correct CommonJS Syntax)
 
-rollupConfig.plugins = [ uglify() ];
-rollupConfig.output.file = 'dist/bundle.min.js';
+// 1. Use require() to import the base config and the terser plugin
+const rollupConfig = require('./rollup.config.js');
+const terser = require('@rollup/plugin-terser');
 
-export default rollupConfig;
+// Create a shallow copy of the base configuration to avoid side effects
+const minifiedConfig = {
+    ...rollupConfig,
+    // Ensure the output property is also copied, if it exists
+    output: { ...rollupConfig.output }
+};
+
+// 2. Set the plugins to ONLY include the terser plugin
+minifiedConfig.plugins = [ terser() ];
+
+// 3. Update the file name
+minifiedConfig.output.file = 'dist/bundle.min.js';
+
+// 4. Use module.exports to export the configuration
+module.exports = minifiedConfig;
diff --git a/rollup.config.js b/rollup.config.js
index 1c55fc75..6d2d7b65 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -1,4 +1,5 @@
-export default {
+// rollup.config.js (CommonJS syntax)
+module.exports = {
   input: 'index.js',
   output: {
     file: 'dist/bundle.js',

From bb9394ee086799eb8ced42b30b6343b282034f60 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Thu, 6 Nov 2025 11:00:08 -0500
Subject: [PATCH 09/17] Updates to README.md

---
 README.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/README.md b/README.md
index 1472abbe..41937d32 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,23 @@ JavaScript Expression Evaluator
 [![CDNJS version](https://img.shields.io/cdnjs/v/expr-eval.svg?maxAge=3600)](https://cdnjs.com/libraries/expr-eval)
 [![Build Status](https://travis-ci.org/silentmatt/expr-eval.svg?branch=master)](https://travis-ci.org/silentmatt/expr-eval)
 
+This fork addresses https://github.com/silentmatt/expr-eval/issues/266, security fix has been committed but was never released to NPM
+Therefore, we publish expr-eval-fork to NPM to work around this issue.
+If expr-eval ever gets released, raise an issue and we'll deprecate this fork.
+
+This fork addresses a security vulnerability identified by CVE-2025-12735.
+An important update with a strict allow-list security model to prevent
+Code Injection (CWE-94) and Prototype Pollution (CWE-1321) vulnerabilities.
+To achieve this, the expression evaluator no longer allows arbitrary
+functions to be passed directly into the evaluation context
+`(.evaluate({ myFunc: function() { ... } }))`. Any external function that
+is intended for use in an expression must be explicitly registered with
+the Parser instance via the parser.functions map prior to evaluation. This
+impacts very few test cases that have been updated in test/*.js. A new
+`test/security.js` highlights the attacks against vulnerbaility
+CVE-2025-12735 that will be prevented.
+
+
 Description
 -------------------------------------
 

From bf1123166bffd04c43ee94aa11e0bb7804259ada Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Thu, 6 Nov 2025 11:06:20 -0500
Subject: [PATCH 10/17] Added notes to test/parser.js

---
 test/parser.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/parser.js b/test/parser.js
index 1a3c1511..bd3831c9 100644
--- a/test/parser.js
+++ b/test/parser.js
@@ -234,6 +234,7 @@ describe('Parser', function () {
         assert.strictEqual(parser.parse('sin;').toString(), '(sin)');
         assert.strictEqual(parser.parse('(sin)').toString(), 'sin');
         assert.strictEqual(parser.parse('sin; (2)^3').toString(), '(sin;(2 ^ 3))');
+	/* After this update, to pass a test function f to be used within an expression, you must now register it. The old, insecure pattern of passing the function directly in the evaluate context: parser.parse('f(sin)').evaluate({ f: myFunc }) will now throw an exception. Instead, you must pre-register the function, which is often best done using a concise Immediate Invoked Function Expression (IIFE) for test cases: (function() { parser.functions.f = myFunc; return parser.parse('f(sin)').evaluate();})(). This explicit registration guarantees the function is trusted and safe for execution. */
         assert.deepStrictEqual((function() { parser.functions.f = function (a, b) { return [ a, b ]; }; return parser.parse('f(sin, sqrt)').evaluate();})(), [ Math.sin, Math.sqrt ]);
         assert.strictEqual(parser.parse('sin').evaluate(), Math.sin);
         assert.strictEqual(parser.parse('cos;').evaluate(), Math.cos);

From 46b2b83a103a3539faf9e515c014fc624c926343 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Thu, 6 Nov 2025 11:09:42 -0500
Subject: [PATCH 11/17] Bumped version big jump and small updates from Gemini
 feedback

---
 package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 215f00ba..847cca04 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "expr-eval",
-  "version": "2.0.3",
+  "version": "3.0.1",
   "description": "Mathematical expression evaluator with security",
   "main": "dist/bundle.js",
   "module": "dist/index.mjs",

From 85b96bdebd33ac2d7177cd78344cb29ae7bc3d0a Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Mon, 17 Nov 2025 23:25:17 -0500
Subject: [PATCH 12/17] Vijay's temp fix for MEMBER vulnerability

---
 src/evaluate.js | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/evaluate.js b/src/evaluate.js
index f9aa992e..746debc6 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -14,22 +14,29 @@ export default function evaluate(tokens, expr, values) {
    * This logic is the core security allowance gate.
    */
   var isAllowedFunc = function (f) {
-      if (typeof f !== 'function') return true;
+      if (typeof f !== 'function') return 1;
 
       for (var key in expr.functions) {
-          if (expr.functions[key] === f) return true;
+          if (expr.functions[key] === f) return 2;
       }
 
-      if (f.__expr_eval_safe_def) return true;
+      if (f.__expr_eval_safe_def) return 3;
 
       for (var key in values) {
           if (typeof values[key] === 'object' && values[key] !== null) {
               for (var subKey in values[key]) {
-                  if (values[key][subKey] === f) return true;
+		  console.log(f,values);
+                  if (values[key][subKey] === f) {
+		      const tf = values[key][subKey];
+		      for (var key in expr.functions) {
+			  if (expr.functions[key] === tf) return 4;
+		      }
+		  }
               }
           }
       }
-      return false;
+
+      return 0;
   };
   /* --- END: LOCAL HELPER FUNCTION FOR SECURITY --- */
 
@@ -143,7 +150,17 @@ export default function evaluate(tokens, expr, values) {
     } else if (type === IEXPREVAL) {
       nstack.push(item);
     } else if (type === IMEMBER) {
-      n1 = nstack.pop();
+	n1 = nstack.pop();
+	if (/^__proto__|prototype|constructor$/.test(item.value)) {
+	    throw new Error('prototype access detected in MEMBER');
+	}
+	console.log(typeof(n1[item.value]));
+	console.log(isAllowedFunc(n1[item.value]));
+	if(typeof(n1) === "object" && (typeof(n1[item.value]) === "function")
+	   && (!isAllowedFunc(n1[item.value]))) {
+	    console.log(n1[item.value]);
+	    throw new Error('Is not an allowed function in MEMBER.');
+	}
       nstack.push(n1[item.value]);
     } else if (type === IENDSTATEMENT) {
       nstack.pop();

From 1a3b379d1e540b74799a275baf922cfbb51a1f4b Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 18 Nov 2025 00:53:43 -0500
Subject: [PATCH 13/17] Almost fixed second vul

---
 src/evaluate.js | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/evaluate.js b/src/evaluate.js
index 746debc6..b7ee6125 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -15,27 +15,26 @@ export default function evaluate(tokens, expr, values) {
    */
   var isAllowedFunc = function (f) {
       if (typeof f !== 'function') return 1;
-
       for (var key in expr.functions) {
           if (expr.functions[key] === f) return 2;
       }
-
-      if (f.__expr_eval_safe_def) return 3;
+      if (f.__expr_eval_safe_def) return 4;
 
       for (var key in values) {
           if (typeof values[key] === 'object' && values[key] !== null) {
               for (var subKey in values[key]) {
-		  console.log(f,values);
                   if (values[key][subKey] === f) {
 		      const tf = values[key][subKey];
 		      for (var key in expr.functions) {
-			  if (expr.functions[key] === tf) return 4;
+			  if (expr.functions[key] === tf) return 5;
+		      }
+		      for (var key of Object.getOwnPropertyNames(Math)) {
+			  if(Math[key] === tf) return 6;
 		      }
 		  }
               }
           }
       }
-
       return 0;
   };
   /* --- END: LOCAL HELPER FUNCTION FOR SECURITY --- */
@@ -136,6 +135,9 @@ export default function evaluate(tokens, expr, values) {
           value: n1,
           writable: false
         });
+	  if (f.__expr_eval_safe_def) {
+	      throw new Error("User self-defined safe definition found");
+	  }
         // *** MARK AS SAFE FOR SECURITY CHECK ***
         Object.defineProperty(f, '__expr_eval_safe_def', {
             value: true,
@@ -154,8 +156,6 @@ export default function evaluate(tokens, expr, values) {
 	if (/^__proto__|prototype|constructor$/.test(item.value)) {
 	    throw new Error('prototype access detected in MEMBER');
 	}
-	console.log(typeof(n1[item.value]));
-	console.log(isAllowedFunc(n1[item.value]));
 	if(typeof(n1) === "object" && (typeof(n1[item.value]) === "function")
 	   && (!isAllowedFunc(n1[item.value]))) {
 	    console.log(n1[item.value]);

From 039e419610f8b07846c9a9f4f1a7171bd34c2953 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 18 Nov 2025 01:11:10 -0500
Subject: [PATCH 14/17] A new fix for MEMBER sub property vul

---
 src/evaluate.js   |  1 -
 test/operators.js | 10 ++++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/evaluate.js b/src/evaluate.js
index b7ee6125..cee26a9d 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -158,7 +158,6 @@ export default function evaluate(tokens, expr, values) {
 	}
 	if(typeof(n1) === "object" && (typeof(n1[item.value]) === "function")
 	   && (!isAllowedFunc(n1[item.value]))) {
-	    console.log(n1[item.value]);
 	    throw new Error('Is not an allowed function in MEMBER.');
 	}
       nstack.push(n1[item.value]);
diff --git a/test/operators.js b/test/operators.js
index d6656983..507ef9ab 100644
--- a/test/operators.js
+++ b/test/operators.js
@@ -171,8 +171,9 @@ describe('Operators', function () {
 
     it('evaluates rhs when lhs is true for AND operator', function () {
       var called = spy(returnFalse);
-
-	assert.strictEqual(Parser.evaluate('true and spies.called()', { spies: {called: called }}), false);
+	var parser = new Parser;
+	parser.functions = {f: called};
+	assert.strictEqual(parser.evaluate('true and spies.called()', { spies: {called: called }}), false);
       assert.strictEqual(called.called, true);
     });
   });
@@ -211,8 +212,9 @@ describe('Operators', function () {
 
     it('evaluates rhs when lhs is false', function () {
       var called = spy(returnTrue);
-
-	assert.strictEqual(Parser.evaluate('false or spies.called()', { spies: {called: called }}), true);
+	var parser = new Parser();
+	parser.functions = {f: called};
+	assert.strictEqual(parser.evaluate('false or spies.called()', { spies: {called: called }}), true);
       assert.strictEqual(called.called, true);
     });
   });

From 25cf147b13d233925b552b0e34e4c1c2a8d0fd12 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 18 Nov 2025 17:18:03 -0500
Subject: [PATCH 15/17] Updated test cases to include @baoquanh Issue #289

---
 test/security.js | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test/security.js b/test/security.js
index d688d488..d61ba0e8 100644
--- a/test/security.js
+++ b/test/security.js
@@ -47,3 +47,18 @@ it('PoC provided by researcher VU#263614 deny child exec process', function() {
 	parser.evaluate('exec("whoami")', context);
     }, Error);
 });
+it('PoC provided by researcher https://github.com/silentmatt/expr-eval/issues/289 by gitHub @baoquanh', function() { 
+   var context = {
+       write: (path, data) => fs.writeFileSync(path, data),
+       cmd: (cmd) => console.log('Executing:', cmd),
+       exec: child_process.execSync
+   };
+
+   var baoquanh = {
+       test: context
+   }
+   var parser = new Parser();
+   assert.throws(() => {
+       parser.evaluate('test.write("pwned.txt","Hello!")', baoquanh)
+   }, Error);
+})

From e312ed551667fed61def43007e51822c34341402 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 18 Nov 2025 17:28:39 -0500
Subject: [PATCH 16/17] Update CHANGELOG.md with newer fix

---
 CHANGELOG.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d026c779..cede8856 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,22 @@
 # Changelog
 
+## [3.0.1] - 2025-11-18
+- Incomplete fix to [CVE-2025-12735](https://github.com/advisories/GHSA-jc85-fpwf-qm7x) has been updated to address the issue identified by @baoquanh in silentmatt#289
+
+## [3.0.0] - 2025-11-07
+
+### Added
+
+- BREAKING: `.evaluate()` no longer allows arbitrary and potentially malicious context to be passed for custom function strings. Such functions need to be defined on `Parser.functions`, e.g. `Parser.functions.f = () => {}` rather than `.evaluate({ f: () => {} })`. This fixes [CVE-2025-12735](https://github.com/advisories/GHSA-jc85-fpwf-qm7x).
+- BREAKING: add exports map to make usage with modern JS environments smoother, not requiring bundlers.
+- BREAKING: require Node 16.9.0 minimum, to support `Object.hasOwn` which is safer than its predecessor `Object.prototype.hasOwnPropery`.
+
 ## [2.0.2] - 2019-09-28
 
 ### Added
 
 - Added non-default exports when using the ES module format. This allows `import { Parser } from 'expr-eval'` to work in TypeScript. The default export is still available for backward compatibility.
+- This fork publishes a security vulnerability fix for prototype pollution. This was committed to the origin project but never published to NPM.
 
 
 ## [2.0.1] - 2019-09-10

From 3e468c2088f4a37dff9b74c53b1a80f6df524fe6 Mon Sep 17 00:00:00 2001
From: Vijay Sarvepalli <vssarvepalli@cert.org>
Date: Tue, 18 Nov 2025 17:48:20 -0500
Subject: [PATCH 17/17] Switched states to true/false

---
 src/evaluate.js | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/evaluate.js b/src/evaluate.js
index cee26a9d..51eb02a4 100644
--- a/src/evaluate.js
+++ b/src/evaluate.js
@@ -14,11 +14,11 @@ export default function evaluate(tokens, expr, values) {
    * This logic is the core security allowance gate.
    */
   var isAllowedFunc = function (f) {
-      if (typeof f !== 'function') return 1;
+      if (typeof f !== 'function') return true;
       for (var key in expr.functions) {
-          if (expr.functions[key] === f) return 2;
+          if (expr.functions[key] === f) return true;
       }
-      if (f.__expr_eval_safe_def) return 4;
+      if (f.__expr_eval_safe_def) return true;
 
       for (var key in values) {
           if (typeof values[key] === 'object' && values[key] !== null) {
@@ -26,16 +26,16 @@ export default function evaluate(tokens, expr, values) {
                   if (values[key][subKey] === f) {
 		      const tf = values[key][subKey];
 		      for (var key in expr.functions) {
-			  if (expr.functions[key] === tf) return 5;
+			  if (expr.functions[key] === tf) return true;
 		      }
 		      for (var key of Object.getOwnPropertyNames(Math)) {
-			  if(Math[key] === tf) return 6;
+			  if(Math[key] === tf) return true;
 		      }
 		  }
               }
           }
       }
-      return 0;
+      return false;
   };
   /* --- END: LOCAL HELPER FUNCTION FOR SECURITY --- */
 
@@ -135,9 +135,6 @@ export default function evaluate(tokens, expr, values) {
           value: n1,
           writable: false
         });
-	  if (f.__expr_eval_safe_def) {
-	      throw new Error("User self-defined safe definition found");
-	  }
         // *** MARK AS SAFE FOR SECURITY CHECK ***
         Object.defineProperty(f, '__expr_eval_safe_def', {
             value: true,