`validateBranchName` used a strict whitelist that excluded `#`,
causing the action to fail on PRs from branches like `put-back-arm64-#2`
with "Invalid branch name" — even though the branch already exists in
git and `#` is permitted by git-check-ref-format.
The validation was designed to prevent command injection. However, every
git call in the action uses `execFileSync`, which bypasses the shell
entirely and passes arguments directly to the kernel's execve. There is
no shell to interpret `#` as a metacharacter, so the strict whitelist was
over-blocking valid names with no security benefit.
Add `#` to the whitelist pattern, and update the JSDoc and error message
to reflect the allowed character set.
Fixes#1137.
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
* fix: Prevent command injection in branch operations
Replace Bun shell template literals with Node.js execFileSync to prevent
command injection attacks via malicious branch names. Branch names from
PR data (headRefName) are now validated against a strict whitelist pattern
before use in git commands.
Changes:
- Add validateBranchName() function with strict character whitelist
- Replace $`git ...` shell templates with execGit() using execFileSync
- Validate all branch names before use in git operations
* fix: Address review comments for branch validation security
- Enhanced execGit JSDoc to explain security benefits of execFileSync
- Added comprehensive branch name validation:
- Leading dash check (prevents option injection)
- Control characters and special git characters (~^:?*[\])
- Leading/trailing period checks
- Trailing slash and consecutive slash checks
- Added -- separator to git checkout commands
- Added 30 unit tests for validateBranchName covering:
- Valid branch names
- Command injection attempts
- Option injection attempts
- Path traversal attempts
- Git-specific invalid patterns
- Control characters and edge cases
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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Co-authored-by: Claude <noreply@anthropic.com>
