GHSA-V53H-F6M7-XCGM
Vulnerability from github – Published: 2026-03-07 02:32 – Updated: 2026-03-11 21:37
VLAI?
Summary
Black's vulnerable version parsing leads to RCE in GitHub Action
Details
Impact
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.
Patches
Version 26.3.0 fixes this vulnerability by tightening the validation of the version field. Users who use the GitHub Action as psf/black@stable will automatically pick up this update.
Workarounds
Do not use the use_pyproject: true option in the psf/black GitHub Action.
Severity ?
{
"affected": [
{
"package": {
"ecosystem": "GitHub Actions",
"name": "psf/black"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "26.3.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-31900"
],
"database_specific": {
"cwe_ids": [
"CWE-20"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-07T02:32:27Z",
"nvd_published_at": "2026-03-11T20:16:15Z",
"severity": "HIGH"
},
"details": "### Impact\n\nBlack provides a [GitHub action](https://black.readthedocs.io/en/stable/integrations/github_actions.html) 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.\n\n### Patches\n\nVersion 26.3.0 fixes this vulnerability by tightening the validation of the `version` field. Users who use the GitHub Action as `psf/black@stable` will automatically pick up this update.\n\n### Workarounds\n\nDo not use the `use_pyproject: true` option in the psf/black GitHub Action.",
"id": "GHSA-v53h-f6m7-xcgm",
"modified": "2026-03-11T21:37:22Z",
"published": "2026-03-07T02:32:27Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/psf/black/security/advisories/GHSA-v53h-f6m7-xcgm"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31900"
},
{
"type": "WEB",
"url": "https://github.com/psf/black/commit/0a2560b981364dde4c8cf8ce9d164c40669a8611"
},
{
"type": "PACKAGE",
"url": "https://github.com/psf/black"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Black\u0027s vulnerable version parsing leads to RCE in GitHub Action"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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