diff --git a/.github/bin/bump_dependency.py b/.github/bin/bump_dependency.py
index e658e4c3d5b1..bae890d62c0c 100644
--- a/.github/bin/bump_dependency.py
+++ b/.github/bin/bump_dependency.py
@@ -140,6 +140,11 @@ def main() -> int:
         default="{repo_url}/compare/{old_version}...{new_version}",
         help="Template for diff URLs",
     )
+    parser.add_argument(
+        "--commit-message-fd",
+        type=int,
+        help="File descriptor to write commit message to",
+    )
 
     args = parser.parse_args()
 
@@ -154,8 +159,9 @@ def main() -> int:
 
     if current_version == latest_version:
         print(f"{args.name}: No update needed (current: {current_version})")
-        with open(os.environ["GITHUB_OUTPUT"], "a") as f:
-            f.write("HAS_UPDATES=false\n")
+        if not args.commit_message_fd:
+            with open(os.environ["GITHUB_OUTPUT"], "a") as f:
+                f.write("HAS_UPDATES=false\n")
         return 0
 
     print(
@@ -181,11 +187,15 @@ def main() -> int:
         args.diff_url_template,
     )
 
-    with open(os.environ["GITHUB_OUTPUT"], "a") as f:
-        f.write("COMMIT_MSG<<EOF\n")
-        f.write(commit_msg)
-        f.write("\nEOF\n")
-        f.write("HAS_UPDATES=true\n")
+    if args.commit_message_fd:
+        with os.fdopen(args.commit_message_fd, "w") as f:
+            f.write(commit_msg)
+    else:
+        with open(os.environ["GITHUB_OUTPUT"], "a") as f:
+            f.write("COMMIT_MSG<<EOF\n")
+            f.write(commit_msg)
+            f.write("\nEOF\n")
+            f.write("HAS_UPDATES=true\n")
 
     return 0
 
diff --git a/.github/bin/bump_downstreams.sh b/.github/bin/bump_downstreams.sh
index eb205c58093d..035c379dc6e8 100755
--- a/.github/bin/bump_downstreams.sh
+++ b/.github/bin/bump_downstreams.sh
@@ -38,7 +38,10 @@ while IFS=: read -r downstream repo ref; do
     ref_pattern="REF: ($ref)"
     replacement_pattern="REF: {new_version}"
 
-    # Run bump_dependency.py
+    # Create a temporary file for this downstream's commit message
+    TEMP_MSG_FILE=$(mktemp)
+
+    # Run bump_dependency.py with commit-message-fd redirected to the temp file
     python3 .github/bin/bump_dependency.py \
         --name "$downstream" \
         --repo-url "$repo_url" \
@@ -47,21 +50,22 @@ while IFS=: read -r downstream repo ref; do
         --current-version-pattern "$ref_pattern" \
         --update-pattern "$replacement_pattern" \
         --comment-pattern "$comment_pattern" \
-        $tag_args
+        --commit-message-fd 3 \
+        $tag_args 3<"$TEMP_MSG_FILE"
 
-    # Check if this downstream had updates
-    if [ -f "$GITHUB_OUTPUT" ]; then
-        if grep -q "HAS_UPDATES=true" "$GITHUB_OUTPUT"; then
-            HAS_ANY_UPDATES=true
-            # Extract commit message for this downstream
-            DOWNSTREAM_MSG=$(sed -n '/COMMIT_MSG<<EOF/,/^EOF$/p' "$GITHUB_OUTPUT" | sed '1d;$d')
-            if [ -n "$COMBINED_COMMIT_MSG" ]; then
-                COMBINED_COMMIT_MSG="$COMBINED_COMMIT_MSG"$'\n\n'"$DOWNSTREAM_MSG"
-            else
-                COMBINED_COMMIT_MSG="$DOWNSTREAM_MSG"
-            fi
+    # Check if this downstream had updates (commit message file has content)
+    if [ -s "$TEMP_MSG_FILE" ]; then
+        HAS_ANY_UPDATES=true
+        DOWNSTREAM_MSG=$(cat "$TEMP_MSG_FILE")
+        if [ -n "$COMBINED_COMMIT_MSG" ]; then
+            COMBINED_COMMIT_MSG="$COMBINED_COMMIT_MSG"$'\n\n'"$DOWNSTREAM_MSG"
+        else
+            COMBINED_COMMIT_MSG="$DOWNSTREAM_MSG"
         fi
     fi
+
+    # Clean up temp file
+    rm -f "$TEMP_MSG_FILE"
 done <<< "$DOWNSTREAMS"
 
 # Set final outputs