CVE-2026-31900
Black's vulnerable version parsing leads to RCE in GitHub Action
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
Black is the uncompromising Python code formatter. Black provides a GitHub action for formatting code. This action supports an option, use_pyproject: true, for reading the version of Black to use from the repository pyproject.toml. A malicious pull request could edit pyproject.toml to use a direct URL reference to a malicious repository. This could lead to arbitrary code execution in the context of the GitHub Action. Attackers could then gain access to secrets or permissions available in the context of the action. Version 26.3.0 fixes this vulnerability.
| CWE | CWE-20 |
| Vendor | psf |
| Product | black |
| Published | Mar 11, 2026 |
| Last Updated | Mar 13, 2026 |
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Affected Versions
psf / black
< 26.3.0