Bug 2567838 (CVE-2026-114134)

Summary: CVE-2026-114134 black: Black: Arbitrary code execution via unvalidated version specification in GitHub Action
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Black GitHub Action. When configured to read project settings from a configuration file, the action fails to validate the specified version identifier. A remote attacker capable of submitting a pull request can supply a reference to external malicious code, leading to arbitrary code execution within the victim repository's continuous integration (CI) workflow environment.
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Description OSIDB Bzimport 2026-11-05 22:30:12 UTC 
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.