CVE-2025-12562: 
GitLab vulnerability analysis and mitigation

CVE-2025-12562 is a denial-of-service vulnerability in GitLab CE/EE's GraphQL API that allows unauthenticated attackers to bypass query complexity limits by sending crafted GraphQL queries, causing a DoS condition. It affects all GitLab CE/EE versions from 11.10 before 18.4.6, 18.5 before 18.5.4, and 18.6 before 18.6.2. The vulnerability was disclosed on December 10–11, 2025, when GitLab released patched versions and the CVE was published. It carries a CVSS v3.1 base score of 7.5 (High) (GitLab Advisory, Red Hat CVE).

The root cause is classified as CWE-770 (Allocation of Resources Without Limits or Throttling): GitLab's GraphQL endpoint fails to properly enforce query complexity limits, allowing specially crafted queries to consume excessive server resources. The attack vector is network-based, requires no authentication, no user interaction, and low attack complexity — an unauthenticated remote attacker can send malicious GraphQL requests directly to the exposed endpoint. The vulnerability was reported to GitLab through the HackerOne bug bounty program by researcher 'joaxcar' and is also tracked in GitLab's internal issue tracker (GitLab Advisory, ENISA EUVD).

Successful exploitation results in a denial-of-service condition affecting the availability of the GitLab instance, with no impact on confidentiality or integrity. An unauthenticated attacker can render GitLab's GraphQL API unresponsive, potentially disrupting CI/CD pipelines, repository access, and all GitLab services dependent on the GraphQL layer. Given the extremely broad version range affected (from version 11.10 onward), the potential scope of impact across self-managed GitLab deployments is significant (GitLab Advisory, Red Hat CVE).

No public proof-of-concept exploit code or active in-the-wild exploitation has been reported for CVE-2025-12562 as of the available data. The EPSS score is approximately 0.062%, indicating a low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. However, the zero-authentication requirement and broad version range make it an attractive target for opportunistic attackers seeking to disrupt GitLab services (GitLab Advisory, Feedly).

1. Reconnaissance: Identify internet-facing GitLab CE/EE instances running versions from 11.10 up to (but not including) 18.4.6, 18.5.4, or 18.6.2 using tools like Shodan or Censys, or by checking the GitLab version endpoint (e.g., /api/v4/version if accessible).
2. Locate GraphQL endpoint: Confirm the GitLab GraphQL API endpoint is accessible, typically at https://<gitlab-host>/api/graphql.
3. Craft complexity-bypassing query: Construct a GraphQL query designed to bypass the server's query complexity limits — for example, deeply nested queries or queries with high field fan-out that evade the complexity calculation logic.
4. Send repeated requests: Repeatedly submit the crafted GraphQL POST requests to the /api/graphql endpoint without any authentication headers, causing the server to allocate excessive resources for each request.
5. Achieve DoS: The server becomes overwhelmed processing the resource-intensive queries, degrading or completely denying service to legitimate users of the GitLab instance (GitLab Advisory).

• Network: High volume of POST requests to /api/graphql from one or more source IPs, particularly without authentication headers; unusual spikes in GraphQL API traffic.
• Logs: GitLab production logs (production.log) showing repeated GraphQL requests with abnormally large or deeply nested query bodies; elevated response times or timeouts on the /api/graphql endpoint.
• Process/System: Elevated CPU or memory consumption by GitLab Puma/Unicorn worker processes; increased database query load correlated with GraphQL endpoint activity.
• Application: GitLab availability alerts or health check failures coinciding with bursts of unauthenticated GraphQL requests (GitLab Advisory).

GitLab has released patched versions 18.4.6, 18.5.4, and 18.6.2 for both CE and EE, and strongly recommends all self-managed installations upgrade immediately. GitLab.com is already running the patched version; GitLab Dedicated customers do not need to take action. No specific configuration-based workaround has been published — upgrading to a fixed version is the primary remediation. As a temporary measure, administrators may consider rate-limiting or restricting access to the /api/graphql endpoint at the network or reverse-proxy level until an upgrade can be performed (GitLab Advisory).

The vulnerability was covered by several cybersecurity news outlets as part of broader reporting on the December 2025 GitLab patch release, which addressed multiple high-severity issues including XSS and DoS vulnerabilities. Coverage appeared in Cyber Security News, Heise, eSecurity Planet, and The Hacker News' weekly recap, generally framing the patch release as significant given the number and severity of issues addressed. The Belgian Centre for Cybersecurity (CCB) issued an advisory warning about the high-severity vulnerabilities in GitLab CE/EE. No notable individual researcher commentary specific to CVE-2025-12562 beyond the HackerOne reporter ('joaxcar') has been identified (GitLab Advisory, Rewterz Advisory).