Python GitHub token leak shows binary files can burn developers too

While Durbin knew that adding personal access tokens (PATs) to source code is bad security practice, the change was only to his local copy of the codebase and was never intended to be pushed remotely. In fact, the automated build and deployment script was supposed to revert local changes, which should have scrubbed the token.

What Durbin didn’t realize was that the token was also included in .pyc (Python compiled bytecode) files generated as part of the build process, and that those files, stored in the __pycache__ folder, were not configured to be excluded from the final Docker image uploaded to Docker Hub.

After being notified by JFrog in late June, the PyPI security team revoked the token and reviewed all GitHub audit logs and account activity for possible signs that the token might have been used maliciously. No evidence of malicious use was found. The cabotage-app version containing the token was published on Docker Hub on March 3, 2023, and was removed on June 21, 2024 — fifteen months later.