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VulnerabilityPublished Updated

CVE-2026-31976: xygeni-action · Embedded Malicious Code

Affects xygeni-actionSource CVE Database V5

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Not known to be exploited · CVSS 9.3 Critical.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.

Contested

Critical score, yet low EPSS after six months
EPSS
0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
xygenixygeni-actionAffected
  • =>= March 3, 2026, <= March 10, 2026
Fixed in–
GitHubxygeni/xygeni-actionpkg:github/xygeni/xygeni-actionOther threatsAffected
  • =v5
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate this threat, organizations should immediately audit their GitHub workflows for references to xygeni/xygeni-action@v5 and update to a known clean and patched version once available. Implement strict GitHub App credential management, including rotating credentials and enforcing least privilege principles to prevent unauthorized tag modifications. Enable branch protection rules and require signed commits and tags to prevent unauthorized changes. Monitor CI runner logs for unusual command execution patterns and network connections indicative of C2 activity. Consider isolating CI runners in segmented environments with limited network access to reduce impact. Finally, incorporate supply chain security best practices such as reproducible builds, artifact signing, and dependency scanning to detect and prevent similar attacks.

Description

CVE-2026-31976 is a critical supply chain vulnerability in the GitHub Action 'xygeni-action' used by the Xygeni Scanner. An attacker with compromised GitHub App credentials injected obfuscated malicious shell code into the action.yml file via unmerged pull requests. Although the PRs were blocked, the attacker moved the mutable v5 tag to point to the malicious commit, causing any workflow referencing xygeni/xygeni-action@v5 between March 3 and March 10, 2026, to execute a command-and-control implant. This implant allowed arbitrary command execution on CI runners for up to 180 seconds per workflow run without requiring authentication or user interaction. The vulnerability represents a high-severity supply chain compromise with a CVSS 9.3 score. Organizations using this GitHub Action during the affected window are at risk of remote code execution and potential further compromise of their CI/CD environments.

References

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