Black: Arbitrary file writes from unsanitized user input in cache file name
Impact
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.
Patches
Fixed in Black 26.3.1.
Workarounds
Do not allow untrusted user input into the value of the --python-cell-magics option.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | black | >= 24.3.0, < 26.3.1 | 26.3.1 |
References
- https://access.redhat.com/security/cve/CVE-2026-32274
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32274.json
- https://access.redhat.com/errata/RHSA-2026:10184
- https://access.redhat.com/errata/RHSA-2026:13545
- https://access.redhat.com/errata/RHSA-2026:13553
- https://github.com/psf/black/releases/tag/26.3.1
- https://github.com/psf/black/security/advisories/GHSA-3936-cmfr-pm3m
- https://bugzilla.redhat.com/show_bug.cgi?id=2447111
- https://github.com/psf/black/commit/4937fe6cf241139ddbfc16b0bdbb5b422798909d
- https://github.com/psf/black/pull/5038
- https://nvd.nist.gov/vuln/detail/CVE-2026-32274
- https://github.com/psf/black/pull/4176
- https://github.com/psf/black/commit/ed770ba4dd50c419148a0fca2b43937a7447e1f9
- https://github.com/psf/black
- https://github.com/pypa/advisory-database/tree/main/vulns/black/PYSEC-2026-2121.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- Weakness (CWE)
CWE-22- Platform
- Python (PyPI)
- Package
black- Disclosed
- 12.03.2026
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-2121 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-3936-cmfr-pm3m - CC BY 4.0
Vulnerability history: black
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 03.2024 03.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
- Medium 1
Disclosures per year
- 2024: 1
- 2025: 0
- 2026: 2
-
Black: Arbitrary file writes from unsanitized user input in cache file name this entry
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