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CVE-2026-61559: CVE-2026-61559: Critical Server-Side Request Forgery and Token Leakage in @zereight/mcp-gitlab

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CVE-2026-61559: Critical Server-Side Request Forgery and Token Leakage in @zereight/mcp-gitlab

Vulnerability ID: CVE-2026-61559
CVSS Score: 9.6
Published: 2026-09-15

A critical Server-Side Request Forgery (SSRF) vulnerability in @zereight/mcp-gitlab allows attackers to leak sensitive GitLab Private-Tokens by supplying an arbitrary external hostname via the X-GitLab-API-URL header when dynamic routing is enabled.

TL;DR

Unauthenticated remote attackers can steal sensitive GitLab Private-Tokens via a Server-Side Request Forgery (SSRF) flaw in gitlab-mcp by injecting a malicious destination host in the X-GitLab-API-URL header.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-918
  • Attack Vector: Network (AV:N)
  • CVSS Score: 9.6 (Critical)
  • EPSS Score: Not indexed (Freshly published)
  • Impact: Credential Theft & GitLab Compromise
  • Exploit Status: Proof of Concept (PoC) available
  • CISA KEV Status: Not Listed

Affected Systems

  • @zereight/mcp-gitlab
  • gitlab-mcp
  • @zereight/mcp-gitlab: >= 0.0.1, < 2.1.27 (Fixed in: 2.1.27)

Code Analysis

Commit: 6ffb4cc

Add dynamic API URL domain validation via resolveTrustedGitLabApiUrl

Mitigation Strategies

  • Disable dynamic routing by setting ENABLE_DYNAMIC_API_URL=false if multi-tenant or multi-instance routing is not required.
  • Configure the GITLAB_ALLOWED_HOSTS environment variable to strict trust limits when dynamic API URLs are mandatory.
  • Upgrade @zereight/mcp-gitlab to version 2.1.27 or higher.

Remediation Steps:

  1. Run 'npm install @zereight/mcp-gitlab@latest' to update the package to version 2.1.27 or later.
  2. If dynamic API URL routing is active, export the 'GITLAB_ALLOWED_HOSTS' environment variable containing your trusted GitLab domains.
  3. Verify the configuration by executing a request with an unlisted domain in 'X-GitLab-API-URL' and confirming it receives an HTTP 400 Bad Request error.

References

Read the full report for CVE-2026-61559 on our website for more details including interactive diagrams and full exploit analysis.

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