CVE-2026-31900
9.8
CRITICAL
CVSS 3.1
EPSS 0.46%
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.
How to fix CVE-2026-31900
To remediate CVE-2026-31900, upgrade the affected package to a fixed version below.
- —upgrade to 26.3.0 or later
Is CVE-2026-31900 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 26.3.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |