CVE-2026-31900 — Black's vulnerable version parsing leads to RCE in GitHub Action
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 versi…
Published: 2026-03-11 · CVSS: 8.7 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7