CVE-2026-31976
xygeni-action v5 tag poisoned with C2 backdoor
Description
xygeni-action is the GitHub Action for Xygeni Scanner. On March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into action.yml. The PRs were blocked by branch protection rules and never merged into the main branch. However, the attacker used the compromised GitHub App credentials to move the mutable v5 tag to point at the malicious commit (4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing @v5 would fetch and execute it. This is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing xygeni/xygeni-action@v5 during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run.
INFO
Published Date :
March 11, 2026, 8:16 p.m.
Last Modified :
March 16, 2026, 7:02 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update the GitHub Action to a secure version.
- Revoke compromised GitHub App credentials immediately.
- Scan repository for unauthorized changes.
- Revert or remove the mutable tag.
Public PoC/Exploit Available at Github
CVE-2026-31976 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-31976.
| URL | Resource |
|---|---|
| https://github.com/xygeni/xygeni-action/issues/54 | Issue Tracking |
| https://github.com/xygeni/xygeni-action/security/advisories/GHSA-f8q5-h5qh-33mh | Vendor Advisory Patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-31976 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-31976
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
GitHub Action that scans GitHub Actions YAMLs for 180+ vulnerabilities, attack paths, and security anti-patterns in less than 10 seconds
bash bash-script github github-actions github-actions-security shell shell-script gha gha-action github-actions-ci githubactions application-security appsec devsecops
Shell
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-31976 vulnerability anywhere in the article.
-
Daily CyberSecurity
The Mutable Tag Trap: Critical 9.4 CVSS Attack on Xygeni GitHub Action Exposes CI/CD Pipelines
In a sophisticated supply chain manipulation, the xygeni-action GitHub Action was recently targeted by a critical “tag poisoning” attack. On March 3, 2026, an attacker utilized compromised credentials ... Read more
-
Daily CyberSecurity
CISA Mandates Urgent Patch for Maximum 10.0 CVSS n8n RCE Flaw
The Cybersecurity and Infrastructure Security Agency (CISA) has officially added a new, high-stakes entry to its Known Exploited Vulnerabilities (KEV) Catalog. The vulnerability, tracked as CVE-2025-6 ... Read more
The following table lists the changes that have been made to the
CVE-2026-31976 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Mar. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:xygeni:xygeni-action:*:*:*:*:*:*:*:* versions from (including) 5.38.0 up to (including) 6.4.0 Added Reference Type GitHub, Inc.: https://github.com/xygeni/xygeni-action/issues/54 Types: Issue Tracking Added Reference Type GitHub, Inc.: https://github.com/xygeni/xygeni-action/security/advisories/GHSA-f8q5-h5qh-33mh Types: Patch, Vendor Advisory -
New CVE Received by [email protected]
Mar. 11, 2026
Action Type Old Value New Value Added Description xygeni-action is the GitHub Action for Xygeni Scanner. On March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into action.yml. The PRs were blocked by branch protection rules and never merged into the main branch. However, the attacker used the compromised GitHub App credentials to move the mutable v5 tag to point at the malicious commit (4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing @v5 would fetch and execute it. This is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing xygeni/xygeni-action@v5 during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/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 Added CWE CWE-506 Added Reference https://github.com/xygeni/xygeni-action/issues/54 Added Reference https://github.com/xygeni/xygeni-action/security/advisories/GHSA-f8q5-h5qh-33mh