Code Formatting Vulnerability in Black Python Formatter by PSF
CVE-2026-114134

8.7HIGH

Key Information:

Vendor

Psf

Status
Black
Vendor
CVE Published:
5 November 2026

What is CVE-2026-114134?

Prior versions of the Black GitHub Action (before 26.10.1) exhibited an input validation flaw whereby specifying 'tool.black.required-version' in the 'pyproject.toml' file could allow an attacker to inject references to malicious code. By manipulating this configuration, an unauthorized user could execute arbitrary code within the context of a victim's repository during the GitHub Actions workflow. This critical flaw has been addressed in version 26.10.1 to ensure that only validated and formally released Black versions can be used.

Affected Version(s)

black < 26.10.1

References

https://github.com/psf/black/security/advisories/GHSA-cg8...
x_refsource_CONFIRM
https://github.com/psf/black/pull/5510
x_refsource_MISC
https://github.com/psf/black/commit/ac1f71563aeccf73cf13e...
x_refsource_MISC

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.