Pip versions prior to 26.1 contain a flaw where the self‑update routine runs after wheel files are installed, at which point it imports well‑known Python modules. The flaw maps to CWE‑829, which concerns the import of untrusted input, and also to CWE‑94, indicating code injection potential. If a malicious wheel is installed, the subsequent import of that wheel’s modules can execute arbitrary code during the self‑update process, potentially compromising the system on which pip runs.

Python installers that use pip before version 26.1, including the official pip packages distributed by the pip maintainers, and any custom builds that bundle an older pip executable.

The CVSS score of 5.3 indicates moderate severity. The EPSS score is less than 1%, indicating a very low exploitation probability, and the vulnerability is not listed in CISA's KEV catalog, suggesting it has not yet been widely exploited. However, the required conditions – the presence of a malicious wheel file and execution of a self‑update – are achievable by a local user with package installation privileges. Consequently, the risk is moderate and mitigation through an official patch is recommended.