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.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-v53h-f6m7-xcgm Black's vulnerable version parsing leads to RCE in GitHub Action
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-11T19:15:20.822Z

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

Link: CVE-2026-31900

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

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

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

Link: CVE-2026-31900

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses