# CVE-2026-31900: black: Black is the uncompromising Python code formatter

CVE-2026-31900 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-31900, released March 11, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-31900
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0052
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 11, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | black Debian 14 | 26.3.1-1 | [DEBIAN-CVE-2026-31900](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31900.md) | Mar 11, 2026 |
| Linux | python-black opensuse-leap 16.0 | 25.1.0-160000.3.1 | [OPENSUSE-SU-2026:20417-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20417-1.md) | Mar 24, 2026 |
| Linux | python-black sles 16.0 | 25.1.0-160000.3.1 | [SUSE-SU-2026:20928-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20928-1.md) | Mar 24, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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