Black CVEs and Security Vulnerabilities

CVE-2026-32274

Black: Arbitrary file writes from unsanitized user input in cache file name

Black is the uncompromising Python code formatter. Starting in version 24.3.0 and prior to version 26.3.1, Black writes a cache file, the name of which is computed from various formatting options. The value of the --python-cell-magics option was placed in the filename without sanitization, which allowed an attacker who controls the value of this argument to write cache files to arbitrary file system locations. Fixed in Black 26.3.1.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Psf Python

Products

Black Black

CVE-2026-31900

Black's vulnerable version parsing leads to RCE in GitHub Action

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.