HighCISA KEVExploited in the wildPublic exploit

GitLab CE/EE Server-Side Request Forgery via CI Lint API

IdentifiersCVE-2021-39935CWE-918· Server-Side Request Forgery (SSRF)

CVE-2021-39935 is a server-side request forgery (SSRF) vulnerability in GitLab Community Edition and Enterprise Edition. It affects all versions starting from 10.5 before 14.3.6, all versions starting from 14.4 before 14.4.4, and all versions starting from 14.5 before 14.5.2. The issue is in the CI Lint API, where unauthorized external users could cause the GitLab server to perform server-side requests. In environments where external users should not have access to this functionality, the flaw allows abuse of the CI Lint API to induce outbound requests from the GitLab instance to attacker-specified destinations, including potentially internal services reachable only from the server.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an unauthorized external user to leverage the GitLab server as an SSRF primitive. This can expose internal network services, cloud instance metadata endpoints, and other resources reachable from the GitLab host but not directly accessible to the attacker. Depending on network topology and reachable services, impact can include internal reconnaissance, access to sensitive metadata or tokens, and pivoting toward additional compromise of adjacent systems or trusted internal services.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict access to the CI Lint API to trusted users and networks only, such as through reverse proxy controls, WAF rules, or network ACLs. Additionally, reduce the GitLab instance’s outbound network reachability to limit access to internal services and cloud metadata endpoints, and monitor for suspicious CI Lint API usage and anomalous outbound requests from the GitLab server.

Remediation

Patch, then assume compromise.

Upgrade GitLab CE/EE to a fixed release. The vulnerable ranges are fixed in 14.3.6, 14.4.4, and 14.5.2. Systems running affected versions should be updated to the appropriate patched version or a later supported release in the relevant branch.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

GitLabGitlabapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

28 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

28 SOURCESView more in app

vulnuNews

Feb 6, 2026

🎓️ Vulnerable U | #154

A GitLab server-side request forgery (SSRF) vulnerability involving the CI Lint API access controls, patched in 2021 but later observed exploited in the wild against still-exposed instances.

bleeping computerNews

Feb 4, 2026

CISA warns of five-year-old GitLab flaw exploited in attacks

A GitLab CE/EE server-side request forgery (SSRF) vulnerability in the CI Lint API that can allow unauthorized external users (in certain configurations) to make server-side requests, potentially enabling access to internal resources.

the hacker newsNews

Feb 4, 2026

CISA Adds Actively Exploited SolarWinds Web Help Desk RCE to KEV Catalog

A server-side request forgery vulnerability in GitLab Community and Enterprise Editions via the CI Lint API that has been observed exploited as part of broader SSRF abuse activity.

security affairsNews

Feb 3, 2026

U.S. CISA adds SolarWinds Web Help Desk, Sangoma FreePBX, and GitLab flaws to its Known Exploited Vulnerabilities catalog

A GitLab Community/Enterprise Edition SSRF vulnerability that has seen active exploitation/scanning activity consistent with automated exploitation or reconnaissance.

+1 more in the timeline

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity17

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2021-39935

NVD

nvd.nist.gov/vuln/detail/CVE-2021-39935

MITRE CWE · CWE-918

Server-Side Request Forgery (SSRF)

Vendor Advisory

gitlab.com/gitlab-org/gitlab/-/issues/346187

Third Party Advisory

gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39935.json

Third Party Advisory

hackerone.com/reports/1236965

US Government Resource

cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-39935