CVE-2025-10868: GitLab CE/EE DOS Vulnerability

CVE-2025-10868 Overview

CVE-2025-10868 affects GitLab Community Edition (CE) and Enterprise Edition (EE) across multiple version branches. The vulnerability stems from certain string conversion methods exhibiting performance degradation when processing large inputs. This behavior falls under [CWE-840] (Business Logic Errors) and can be leveraged to consume server resources.

The issue impacts all versions from 17.4 before 18.2.7, 18.3 before 18.3.3, and 18.4 before 18.4.1. An unauthenticated attacker can trigger the condition over the network without user interaction, resulting in limited availability impact on the affected GitLab instance.

Critical Impact
Remote unauthenticated attackers can degrade GitLab availability by submitting large inputs that trigger inefficient string conversion routines.

Affected Products

GitLab CE/EE versions 17.4 through 18.2.6
GitLab CE/EE versions 18.3 through 18.3.2
GitLab CE/EE version 18.4.0

Discovery Timeline

2025-09-26 - CVE-2025-10868 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-10868

Vulnerability Analysis

The flaw resides in string conversion methods within GitLab CE/EE. When these methods receive unusually large inputs, their execution time scales inefficiently, consuming CPU and memory beyond expected thresholds. This behavior maps to an algorithmic complexity issue that attackers can exploit for denial of service.

Because the affected code paths are reachable over the network without authentication, any exposed GitLab instance is a potential target. The impact is limited to availability, with no confidentiality or integrity implications.

Root Cause

The root cause is inefficient handling of large string inputs in specific conversion routines within the GitLab codebase. The routines do not enforce input size limits or use algorithms with predictable performance characteristics. As input length grows, processing time increases disproportionately, exhausting server resources.

Attack Vector

An attacker sends crafted requests containing large string payloads to endpoints that invoke the vulnerable conversion methods. Repeated or concurrent requests amplify resource consumption, degrading service for legitimate users. Refer to the GitLab Issue Discussion for additional technical context.

Detection Methods for CVE-2025-10868

Indicators of Compromise

Sustained CPU or memory spikes on GitLab application servers without correlated legitimate workload increases
Elevated request latency and 5xx error rates from GitLab web or API endpoints
Repeated inbound HTTP requests carrying abnormally large string parameters or body payloads

Detection Strategies

Monitor GitLab application logs for requests with unusually large payload sizes targeting API or web endpoints
Correlate resource utilization metrics with request volume to identify low-request, high-resource patterns typical of algorithmic complexity attacks
Alert on prolonged worker process saturation or Puma/Sidekiq queue backlogs

Monitoring Recommendations

Track GitLab instance versions across the environment and flag any running versions below 18.2.7, 18.3.3, or 18.4.1
Implement rate limiting metrics and dashboards at the reverse proxy or WAF tier fronting GitLab
Enable structured logging for request size and processing duration to baseline normal behavior

How to Mitigate CVE-2025-10868

Immediate Actions Required

Upgrade GitLab CE/EE to version 18.2.7, 18.3.3, 18.4.1, or later depending on the deployed branch
Restrict network exposure of GitLab instances to trusted networks or VPNs where feasible
Enforce request size limits at the ingress proxy or load balancer in front of GitLab

Patch Information

GitLab released fixes in versions 18.2.7, 18.3.3, and 18.4.1. Administrators running any affected version from 17.4 onward should upgrade to the appropriate patched release. See the GitLab Issue Discussion for tracking details.

Workarounds

Configure the upstream web server or reverse proxy to reject requests exceeding a reasonable body or parameter size
Apply rate limiting to unauthenticated endpoints to reduce the impact of repeated abusive requests
Monitor and auto-restart worker processes that exceed resource thresholds until patching is complete

bash

# Example NGINX configuration to cap request body size in front of GitLab
http {
    client_max_body_size 10m;
    client_body_buffer_size 128k;

    limit_req_zone $binary_remote_addr zone=gitlab_api:10m rate=30r/m;

    server {
        listen 443 ssl;
        server_name gitlab.example.com;

        location /api/ {
            limit_req zone=gitlab_api burst=10 nodelay;
            proxy_pass http://gitlab_upstream;
        }
    }
}