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Advisory record · GHSA-cg8m-r9f2-5wm2

Black: GitHub Action installs unvalidated required-version from pyproject.toml

CVSS 8.7 High

Published by the GitHub Advisory Database at 22 Oct 2026, 16:18 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
blackPyPI<26.10.126.10.1
Identifiers
GHSA-cg8m-r9f2-5wm2 · CVE-2026-114134
Weakness (CWE)
CWE-829
Tags
Published
22 Oct 2026
Updated
22 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Black versions before 26.10.1 have a vulnerability in the GitHub Action bundled with Black when `use_pyproject` is set to True: the version read from `tool.black.required-version` in pyproject.toml is installed without validation. An attacker who can submit a pull request to the victim's repository could point this value at a malicious source and run code in the context of the repository. Upgrade to Black 26.10.1 or later.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.7 High 4.0 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 CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS No score.

Timeline

  1. 31 Oct 2026, 14:08 UTC First seen by agentprime
  2. 31 Oct 2026, 14:08 UTC Confirmed by OSV
  3. 5 Nov 2026, 20:22 UTC Confirmed by the CVE List
  4. 5 Nov 2026, 21:18 UTC Confirmed by NVD

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.