Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-31900

33
FAUCET Score

CVE-2026-31900 affects the Black GitHub Action, where a vulnerability in its `use_pyproject: true` option allows a malicious pull request to direct the action to use a Black version from a malicious repository. This CRITICAL vulnerability, with a CVSS score of 9.8, enables arbitrary code execution within the GitHub Action's context, potentially compromising secrets and permissions. The attack is network-based with low complexity. There is currently no evidence of active exploitation, nor are public exploit tools or significant community discussion available for this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 26.3.0CPE matchmatch criteria
cpe:2.3:a:python:black:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

8.7HIGH

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
VS Confidentiality
HIGH
VS Integrity
HIGH
VS Availability
HIGH
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.46%
Probability of exploitation in next 30 days
EPSS Percentile
37.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0046 is in the 15th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

actionspatch availablevia ghsa
Product: psf/blackFixed in: 26.3.0

Vendor Advisories (1)

actionsGHSA-v53h-f6m7-xcgmhigh

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

Mar 7, 2026

References

github.com / psf/black/commit/0a2560b981364dde4c8cf8ce9d164c40669a8611
Patch
github.com / psf/black/security/advisories/GHSA-v53h-f6m7-xcgm
MitigationVendor Advisory