CVE-2026-1725: GitLab CE/EE Denial of Service Vulnerability

CVE-2026-1725 Overview

GitLab has remediated a denial of service vulnerability in GitLab CE/EE affecting versions from 18.9 before 18.9.1. Under certain conditions, this vulnerability allows an unauthenticated user to cause denial of service by sending specially crafted requests to a CI jobs API endpoint. The vulnerability is classified as CWE-770 (Allocation of Resources Without Limits or Throttling), indicating that the affected endpoint lacks proper resource consumption controls.

Critical Impact

Unauthenticated attackers can disrupt GitLab CI/CD operations by exhausting server resources through malicious API requests, potentially affecting software delivery pipelines and development workflows.

Affected Products

• GitLab Community Edition (CE) versions 18.9 before 18.9.1
• GitLab Enterprise Edition (EE) versions 18.9 before 18.9.1

Discovery Timeline

• 2026-02-25 - CVE-2026-1725 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-1725

Vulnerability Analysis

This vulnerability exists in GitLab's CI jobs API endpoint and stems from improper resource allocation controls (CWE-770). The flaw allows unauthenticated external attackers to consume excessive server resources by sending specially crafted HTTP requests over the network. No user interaction is required to exploit this vulnerability, and the attack can be conducted remotely without authentication credentials.

The root cause lies in the CI jobs API endpoint failing to implement adequate rate limiting or resource consumption boundaries. When processing certain types of requests, the endpoint does not properly validate or throttle incoming traffic, enabling an attacker to exhaust server resources and degrade service availability.

Root Cause

The vulnerability is attributed to CWE-770: Allocation of Resources Without Limits or Throttling. This weakness occurs when the software allocates resources without defining appropriate limits, allowing attackers to consume those resources and cause denial of service conditions. In this case, the CI jobs API endpoint lacks sufficient safeguards to prevent resource exhaustion from maliciously crafted requests.

Attack Vector

The attack is conducted over the network (Attack Vector: Network) and requires no authentication (Privileges Required: None) or user interaction (User Interaction: None). An attacker can exploit this vulnerability by:

1. Identifying the vulnerable GitLab CI jobs API endpoint
2. Crafting malicious HTTP requests designed to consume excessive server resources
3. Sending a high volume of these requests to exhaust available resources
4. Causing denial of service for legitimate GitLab users

The vulnerability impacts system availability but does not affect confidentiality or integrity of data. Technical details regarding the specific exploitation method can be found in the HackerOne Security Report #3519773 and the GitLab Issue Discussion.

Detection Methods for CVE-2026-1725

Indicators of Compromise

• Unusual spike in requests to GitLab CI jobs API endpoints
• Server resource exhaustion (high CPU, memory utilization) coinciding with API traffic
• Elevated error rates or timeouts from GitLab CI/CD services
• Log entries showing repeated requests from single or clustered IP addresses targeting CI API endpoints

Detection Strategies

• Monitor GitLab application logs for anomalous patterns in CI jobs API request volume
• Implement network-level monitoring to detect high-frequency requests to CI/CD endpoints
• Configure alerting for sudden increases in API error rates or response latency
• Review web application firewall (WAF) logs for blocked or suspicious requests targeting GitLab

Monitoring Recommendations

• Enable detailed logging for GitLab API endpoints, particularly CI/CD related services
• Deploy rate limiting at the load balancer or reverse proxy level for API endpoints
• Implement real-time monitoring dashboards tracking GitLab API performance metrics
• Configure automated alerts for resource consumption anomalies on GitLab servers

How to Mitigate CVE-2026-1725

Immediate Actions Required

• Upgrade GitLab CE/EE to version 18.9.1 or later immediately
• Review GitLab logs for any indication of exploitation attempts
• Implement temporary rate limiting on CI jobs API endpoints if immediate patching is not possible
• Monitor server resource utilization for signs of ongoing denial of service attempts

Patch Information

GitLab has released version 18.9.1 which addresses this vulnerability. Organizations running affected versions should apply the patch as soon as possible. Detailed patch information is available in the GitLab Patch Release Announcement.

Workarounds

• Implement rate limiting at the network edge using a WAF or reverse proxy to restrict API request frequency
• Configure firewall rules to limit access to CI jobs API endpoints to trusted IP ranges
• Deploy load balancer health checks to automatically detect and isolate overloaded GitLab instances
• Consider temporarily restricting unauthenticated access to CI API endpoints until patching is complete

# Example nginx rate limiting configuration for GitLab CI API
# Add to nginx configuration for GitLab
limit_req_zone $binary_remote_addr zone=ci_api_limit:10m rate=10r/s;

location ~ ^/api/v4/projects/.*/jobs {
    limit_req zone=ci_api_limit burst=20 nodelay;
    limit_req_status 429;
    proxy_pass http://gitlab_upstream;
}