GitPython versions older than 3.1.55 allow attackers to inject URLs that contain environment variable references during Remote.create() and Submodule.add() calls. The library incorrectly expands these variables into .git/config and .gitmodules files, which are then transmitted to external hosts when a fetch or pull operation occurs. This flaw enables a remote attacker to harvest sensitive configuration data that the application stores in environment variables, resulting in a confidentiality breach based on CWE‑200.

The vulnerability affects the GitPython library maintained by the gitpython‑developers. All releases before 3.1.55 are impacted. Users embedding GitPython in applications or services that perform remote Git operations with potentially untrusted URLs are at risk.

The CVSS score of 8.7 indicates high severity. Because the flaw requires the attacker to supply a malicious URL that triggers a fetch or pull, the attack vector is remote and depends on an active network connection that performs a Git operation. Although the EPSS score is currently unavailable, the vulnerability is not listed in the CISA KEV catalog, suggesting that there may not yet be widespread exploitation, but the high CVSS rating warrants urgent action. An attacker could submit a crafted URL to a service that pulls from a repository, causing the service to expand environment variables and expose internal secrets to an external host.