GitProxy is an application that stands between developers and a Git remote endpoint. In versions 1.19.1 and below, attackers can inject extra commits into the pack sent to GitHub, commits that aren’t pointed to by any branch. Although these “hidden” commits never show up in the repository’s visible history, GitHub still serves them at their direct commit URLs.

This lets an attacker exfiltrate sensitive data without ever leaving a trace in the branch view. We rate this a High‑impact vulnerability because it completely compromises repository confidentiality. This is fixed in version 1.19.2.