The vulnerability stems from the virtualenv app‑data seeder (CWE‑377) leaving an environment linked to temporary package files that are deleted after creation. Consequently, the environment depends on a cache path controlled by an external source, allowing a dangling symlink to point to an untrusted location. An attacker who can influence the environment variable or configuration file that enables symlink_app_data could create such a malicious symlink. Once the virtual environment is activated, code from the unintended location may be executed, providing local code execution within the user’s environment.

The flaw affects the Python package creator pypa’s virtualenv. Versions 21.14.8 and 21.14.9, as well as any installation that has not been updated to 21.14.10 or later, are vulnerable. Older or newer releases are not susceptible.

The CVSS score of 4.4 signals moderate severity. EPSS is < 1% and the vulnerability is not listed in the CISA KEV catalog. The weakness originates from improper handling of temporary data (CWE‑377), which leads to dangling symbolic links that depend on a cache path beyond the host’s control. The most probable attack vector is local, inferred from the fact that an attacker must affect the environment variable or configuration file that enables symlink_app_data to create the vulnerable environment. Exploitation requires the target to build or activate a virtual environment with the compromised settings, and the risk of exploitation is low to moderate; however, because remote access is not needed, any user with permission to create virtualenvs faces potential compromise.