Branch names starting with an underscore (e.g. _release/v1.2.3) are valid
per git check-ref-format but were rejected by validateBranchName's
first-character whitelist. Since setupBranch validates a PR's baseRefName
after checkout, the action failed on every open PR targeting such a
branch. A leading underscore carries no option-injection risk (only a
leading dash does, which is still rejected separately).
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
`validateBranchName` rejects branch names containing `@`, even though
`git check-ref-format` permits `@` and GitHub itself accepts such
branches. PRs whose head or base branch contains an `@` fail validation
in-process before any git operation, so the action errors out
immediately.
Branch names with `@` show up in real workflows: ticket conventions
like "TICKET-123@add-feature" (#998), leading-prefix conventions like
"@hotfix/...", and agent tooling that appends "@<sessionid>" (#1305).
There is no workaround other than renaming the branch, which is often
not under the user's control.
Branch names are never passed through a shell (git calls use
execFileSync argv arrays), so `@` carries no injection risk. This is
the same reasoning used to add `#` in #1167, `+` in #1248, and `,` in
#1310. The bare name "@" (HEAD shorthand in git revision syntax) and
the "@{" reflog sequence are still rejected.
- Add `@` to the validateBranchName whitelist regex, including the
leading position (the leading-character rule blocks option injection
via `-`, which `@` cannot cause)
- Reject the bare name "@" with a dedicated check
- Update the surrounding comment, JSDoc, and error message to match
- Add test cases for @-containing names and bare "@"
Fixes#998
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
`validateBranchName` rejects branch names containing a comma, even
though `git check-ref-format` permits commas and GitHub itself accepts
them. PRs whose head branch contains a `,` fail validation in-process
before any git operation, so the action errors out immediately.
Branch names with commas show up in real workflows when names are
derived from titles, place names, or external identifiers (e.g.
"feature/paris,france"). There is no workaround other than renaming
the branch, which is often not under the user's control.
All git calls in this file use execFileSync with an argv array, so no
shell interpretation occurs and `,` carries no injection risk. This is
the same reasoning used to add `#` in #1167 and `+` in #1248.
- Add `,` to the validateBranchName whitelist regex
- Update the surrounding comment and error message to match
- Add a test case covering commas in title-derived branch names
Fixes#1300
Claude Code's EnterWorktree tool converts "/" to "+" when generating
branch names from worktree names (e.g. EnterWorktree("feat/foo") creates
branch "worktree-feat+foo"). The strict whitelist in validateBranchName
rejected these names, causing claude-code-action to fail on any PR opened
from an EnterWorktree-generated branch.
Since all git calls use execFileSync (not shell interpolation), "+" carries
no command injection risk — the same rationale used for allowing "#".
Git itself permits "+" in branch names per git-check-ref-format.
Fixes: https://github.com/anthropics/claude-code-action/issues/1244
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
`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>
---------
Co-authored-by: Claude <noreply@anthropic.com>
