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Environment Variable Exfiltration in GitPython

GitPython versions prior to 3.1.52 are vulnerable to environment variable exfiltration when an attacker provides a crafted remote URL to the Repo.clone_from() method.

GitPython versions before 3.1.52 contain a critical vulnerability in the Repo.clone_from() method, which improperly handles remote URL inputs. On non-Cygwin platforms, the library uses os.path.expandvars() on the provided URL string before executing the underlying git clone command. This behavior allows an attacker capable of influencing the remote URL argument to inject shell-style environment variable tokens, such as $AWS_SECRET_ACCESS_KEY or $GITHUB_TOKEN. When Repo.clone_from() is called, the library resolves these tokens to the actual values present in the hosting process's environment. The process then attempts to connect to a remote host specified in the crafted URL, effectively leaking the environment variable value to an attacker-controlled server. This vulnerability poses a significant risk to CI/CD pipelines, automated build systems, and any application that uses GitPython to interact with user-provided or untrusted repository URLs.

Impact

The vulnerability allows for the unauthorized exfiltration of sensitive environment variables, including credentials, API keys, and tokens stored in the memory space of the process utilizing GitPython. Successful exploitation can lead to a complete compromise of cloud service accounts, source code repositories, and other integrated systems relying on environment-based authentication. The scope of impact is dependent on the sensitivity of the variables present in the environment where the affected GitPython library is executing.

Recommendation

  • Update GitPython to version 3.1.52 or later immediately to patch the vulnerable Repo.clone_from() implementation.
  • Audit applications utilizing GitPython to determine if repository URLs are derived from user input or external, untrusted sources.
  • Implement strict allowlisting for repository URLs in applications that must clone external repositories, ensuring they point only to trusted, expected domains.
  • Rotate any credentials or tokens that may have been exposed in environment variables if the application environment was potentially reachable by untrusted inputs during the period of vulnerability.