The GitHub CLI is GitHub’s official command line tool. A security vulnerability has been identified in GitHub CLI that could create or overwrite files in unintended directories when users download a malicious GitHub Actions workflow artifact through gh run download. This vulnerability stems from a GitHub Actions workflow artifact named .. when downloaded using gh run download. The artifact name and --dir flag are used to determine the artifact’s download path. When the artifact is named .., the resulting files within the artifact are extracted exactly 1 directory higher than the specified --dir flag value. This vulnerability is fixed in 2.63.1.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.