CVE-2025-13436: GitLab CI Denial of Service Vulnerability

CVE-2025-13436 Overview

A denial of service vulnerability has been identified in GitLab Community Edition (CE) and Enterprise Edition (EE) that allows authenticated users to cause excessive resource consumption through specially crafted CI-related inputs. This vulnerability affects a wide range of GitLab versions spanning multiple years of releases, making it a significant concern for organizations running self-managed GitLab instances.

The vulnerability is classified as CWE-770 (Allocation of Resources Without Limits or Throttling), indicating that the application fails to properly limit resource allocation when processing certain CI pipeline configurations or related inputs.

Critical Impact

Authenticated attackers can exhaust server resources and cause service disruption to GitLab instances, potentially affecting development workflows, CI/CD pipelines, and collaboration across entire organizations.

Affected Products

• GitLab Community Edition (CE) versions 13.7 to 18.8.6
• GitLab Enterprise Edition (EE) versions 13.7 to 18.8.6
• GitLab CE/EE versions 18.9.0 to 18.9.2
• GitLab CE/EE version 18.10.0

Discovery Timeline

• 2026-03-25 - CVE-2025-13436 published to NVD
• 2026-03-25 - GitLab releases security patch (versions 18.8.7, 18.9.3, 18.10.1)
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2025-13436

Vulnerability Analysis

This denial of service vulnerability stems from improper resource management within GitLab's CI/CD processing functionality. When authenticated users submit certain CI-related inputs, the application allocates system resources without implementing adequate limits or throttling mechanisms. This allows attackers to craft malicious inputs that consume excessive CPU, memory, or other system resources, ultimately degrading or disrupting service availability for legitimate users.

The vulnerability requires authentication, meaning attackers must have valid credentials to a GitLab instance. However, given that many GitLab deployments allow self-registration or have numerous users with varying trust levels, this authentication requirement provides limited protection in practice.

Root Cause

The root cause lies in CWE-770: Allocation of Resources Without Limits or Throttling. GitLab's CI processing components fail to implement proper bounds checking or rate limiting when handling specific input types. This allows resource-intensive operations to execute without constraints, enabling attackers to monopolize system resources through carefully constructed CI configurations or related inputs.

Attack Vector

The attack is network-accessible and requires low-privilege authenticated access. An attacker with a valid GitLab account can exploit this vulnerability by:

1. Authenticating to the target GitLab instance
2. Submitting specially crafted CI-related inputs designed to trigger excessive resource consumption
3. Repeating the process to amplify the denial of service impact

The attack does not require user interaction and can be automated. While specific technical details have been reported through HackerOne Report #3418149, the exact exploitation mechanism involves manipulating CI pipeline configurations or related inputs to trigger unbounded resource allocation within GitLab's backend processing.

Detection Methods for CVE-2025-13436

Indicators of Compromise

• Unusual spikes in CPU or memory utilization on GitLab servers correlated with CI pipeline activity
• Abnormal patterns in CI job submissions from specific user accounts
• System logs showing resource exhaustion warnings or out-of-memory conditions
• Degraded GitLab performance or timeouts during CI/CD operations

Detection Strategies

• Monitor GitLab application logs for unusual CI pipeline creation patterns or errors
• Implement resource utilization alerting with thresholds for CPU, memory, and I/O
• Track per-user CI activity rates to identify anomalous submission patterns
• Review audit logs for repeated CI-related API calls from specific accounts

Monitoring Recommendations

• Configure GitLab's built-in monitoring to alert on resource consumption anomalies
• Deploy application performance monitoring (APM) tools to track CI processing latency
• Establish baseline metrics for normal CI activity to facilitate anomaly detection
• Enable detailed logging for CI/CD operations to support forensic analysis

How to Mitigate CVE-2025-13436

Immediate Actions Required

• Upgrade GitLab CE/EE to patched versions: 18.8.7, 18.9.3, or 18.10.1
• Review recent CI pipeline activity for signs of exploitation attempts
• Consider implementing additional rate limiting for CI pipeline creation if upgrade cannot be performed immediately
• Audit user accounts with CI/CD permissions to ensure principle of least privilege

Patch Information

GitLab has released security patches addressing this vulnerability in the following versions:

Organizations should upgrade to the latest patched version appropriate for their deployment. The official patch release announcement is available at the GitLab Patch Release page.

Workarounds

• Implement network-level rate limiting for GitLab CI/CD API endpoints
• Restrict CI pipeline creation permissions to trusted users only
• Configure resource quotas and limits at the infrastructure level (containers, VMs)
• Monitor and set alerts for abnormal resource consumption patterns
• Consider temporarily disabling self-registration if not operationally required

# Example: Verify GitLab version to confirm patch status
gitlab-rake gitlab:env:info | grep "GitLab"

# Example: Review CI pipeline activity logs
gitlab-ctl tail sidekiq | grep -i "ci_pipeline"