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.
History

Thu, 12 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 12 Mar 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Psf
Psf black
Vendors & Products Psf
Psf black

Wed, 11 Mar 2026 19:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Black's vulnerable version parsing leads to RCE in GitHub Action
Weaknesses CWE-20
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-12T19:59:41.362Z

Reserved: 2026-03-09T21:59:02.689Z

Link: CVE-2026-31900

cve-icon Vulnrichment

Updated: 2026-03-12T19:59:38.486Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-11T20:16:15.960

Modified: 2026-03-12T21:08:22.643

Link: CVE-2026-31900

cve-icon Redhat

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