Black is the uncompromising Python code formatter. Prior to 26.10.1, the Black GitHub Action with use_pyproject: true accepts tool.black.required-version from pyproject.toml without validating that it is a released Black version specifier. An attacker who can submit a pull request can change that field to a direct reference to attacker-controlled code, causing the workflow to install and execute the code in the victim repository's GitHub Actions context. This issue is fixed in version 26.10.1.

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Vendors Products
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-cg8m-r9f2-5wm2 Black: GitHub Action installs unvalidated required-version from pyproject.toml
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 06 Nov 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Thu, 05 Nov 2026 22:00:00 +0000

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

Thu, 05 Nov 2026 20:30:00 +0000

Type Values Removed Values Added
Description Black is the uncompromising Python code formatter. Prior to 26.10.1, the Black GitHub Action with use_pyproject: true accepts tool.black.required-version from pyproject.toml without validating that it is a released Black version specifier. An attacker who can submit a pull request can change that field to a direct reference to attacker-controlled code, causing the workflow to install and execute the code in the victim repository's GitHub Actions context. This issue is fixed in version 26.10.1.
Title Black: GitHub Action installs unvalidated required-version from pyproject.toml
Weaknesses CWE-829
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: 2026-11-05T20:22:14.467Z

Reserved: 2026-10-20T21:53:58.473Z

Link: CVE-2026-114134

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-05T21:18:36.887

Modified: 2026-11-05T21:18:36.887

Link: CVE-2026-114134

cve-icon Redhat

Severity : Important

Publid Date: 2026-11-05T20:22:14Z

Links: CVE-2026-114134 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-05T22:15:14Z

Weaknesses