CVE-2026-1458: GitLab Denial of Service Vulnerability

CVE-2026-1458 Overview

A denial of service vulnerability has been identified in GitLab Community Edition (CE) and Enterprise Edition (EE) that affects a wide range of versions spanning from 8.0 through recent releases. This vulnerability allows unauthenticated attackers to cause service disruption by uploading specially crafted malicious files under certain conditions. The flaw is categorized under CWE-770 (Allocation of Resources Without Limits or Throttling) and CWE-434 (Unrestricted Upload of File with Dangerous Type), indicating weaknesses in both resource management and file upload validation mechanisms.

Critical Impact

Unauthenticated attackers can exploit this vulnerability to cause denial of service conditions on GitLab instances, potentially disrupting development workflows and CI/CD pipelines for entire organizations without requiring any authentication.

Affected Products

• GitLab Community Edition (CE) versions 8.0 before 18.6.6
• GitLab Enterprise Edition (EE) versions 18.7 before 18.7.4
• GitLab CE/EE versions 18.8 before 18.8.4

Discovery Timeline

• 2026-02-10 - GitLab releases security patch (versions 18.6.6, 18.7.4, 18.8.4)
• 2026-02-11 - CVE-2026-1458 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2026-1458

Vulnerability Analysis

This vulnerability exploits weaknesses in GitLab's file upload handling mechanism, combining improper resource allocation controls (CWE-770) with insufficient file upload validation (CWE-434). The attack can be executed remotely over the network without requiring authentication, user interaction, or elevated privileges, making it particularly dangerous for internet-facing GitLab instances.

The vulnerability impacts system availability without affecting confidentiality or integrity. When exploited, the malicious file upload triggers resource exhaustion conditions that can render the GitLab service unavailable to legitimate users. The "certain conditions" mentioned in the advisory suggest the vulnerability may be dependent on specific server configurations or upload pathways.

Root Cause

The root cause stems from inadequate validation and resource throttling mechanisms in GitLab's file upload functionality. The combination of CWE-770 and CWE-434 indicates that the application fails to properly limit resource consumption during file processing and does not adequately validate uploaded file characteristics. This allows attackers to craft files that consume excessive server resources during processing, leading to denial of service conditions.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can remotely target vulnerable GitLab instances by:

1. Identifying publicly accessible GitLab upload endpoints
2. Crafting malicious files designed to exhaust server resources during processing
3. Uploading these files through the vulnerable endpoint
4. Triggering resource exhaustion that impacts service availability

The attack does not require any special privileges and can be launched by completely unauthenticated users, significantly lowering the barrier for exploitation.

Detection Methods for CVE-2026-1458

Indicators of Compromise

• Unusual spikes in file upload activity from unknown or suspicious IP addresses
• Server resource exhaustion patterns (high CPU, memory, or disk I/O) correlated with upload requests
• GitLab service crashes or restarts coinciding with upload activities
• Abnormally large or malformed files appearing in upload directories

Detection Strategies

• Monitor GitLab access logs for high-volume upload requests from single sources
• Implement alerting on unusual resource consumption patterns during file processing operations
• Track failed service health checks and correlate with upload activity timestamps
• Review application logs for file processing errors or timeouts

Monitoring Recommendations

• Configure resource usage alerts on GitLab application servers to detect resource exhaustion attempts
• Implement network-level monitoring for anomalous traffic patterns to upload endpoints
• Enable detailed audit logging for all file upload operations in GitLab
• Deploy web application firewall (WAF) rules to inspect and limit file upload payloads

How to Mitigate CVE-2026-1458

Immediate Actions Required

• Upgrade GitLab CE/EE to patched versions: 18.6.6, 18.7.4, or 18.8.4 immediately
• Review access logs for evidence of exploitation attempts targeting upload functionality
• Consider temporarily restricting file upload capabilities if immediate patching is not possible
• Implement rate limiting on upload endpoints at the network or WAF level

Patch Information

GitLab has released patched versions to address this vulnerability. Organizations should upgrade to the following versions based on their current deployment:

• For versions in the 18.6.x branch: upgrade to 18.6.6
• For versions in the 18.7.x branch: upgrade to 18.7.4
• For versions in the 18.8.x branch: upgrade to 18.8.4

Detailed patch information is available in the GitLab Patch Release Announcement. Additional technical details can be found in the GitLab Issue Discussion and the HackerOne Report #3517644.

Workarounds

• Implement strict rate limiting on all file upload endpoints using reverse proxy or WAF configurations
• Configure resource limits (memory, CPU) for GitLab worker processes to contain potential resource exhaustion
• Restrict upload functionality to authenticated users only if business requirements permit
• Deploy network-level controls to limit upload request sizes and frequencies from individual IP addresses

# Example nginx rate limiting configuration for upload endpoints
# Add to GitLab nginx configuration
limit_req_zone $binary_remote_addr zone=upload_limit:10m rate=10r/m;

location ~ ^/uploads {
    limit_req zone=upload_limit burst=5 nodelay;
    # Additional upload restrictions
    client_max_body_size 10m;
}