CVE-2025-69413: Gitea Auth Bypass Vulnerability

CVE-2025-69413 Overview

CVE-2025-69413 is an information disclosure vulnerability in Gitea, a self-hosted Git service, affecting versions prior to 1.25.2. The vulnerability exists in the /api/v1/user endpoint, which returns different responses for failed authentication attempts depending on whether a username exists in the system. This behavior allows attackers to enumerate valid usernames through the API, which can be leveraged for subsequent attacks such as credential stuffing or targeted phishing campaigns.

Critical Impact

Attackers can enumerate valid usernames in Gitea installations, enabling targeted authentication attacks and reconnaissance activities against organization repositories.

Affected Products

• Gitea versions prior to 1.25.2
• Self-hosted Gitea instances with exposed API endpoints
• Gitea installations accessible over the network

Discovery Timeline

• 2026-01-01 - CVE CVE-2025-69413 published to NVD
• 2026-01-06 - Last updated in NVD database

Technical Details for CVE-2025-69413

Vulnerability Analysis

This vulnerability is classified as CWE-204 (Observable Response Discrepancy), where an application provides different responses to identical requests based on internal state that should not be externally observable. In the case of Gitea, the /api/v1/user endpoint exhibits distinct response patterns when authentication fails—one pattern for valid usernames with incorrect passwords, and another pattern for non-existent usernames.

The discrepancy allows unauthenticated attackers to probe the API systematically and build a list of valid user accounts. This information disclosure is particularly concerning for organizations using Gitea for private repositories, as it exposes the existence of user accounts that should remain confidential.

Root Cause

The root cause of this vulnerability lies in the authentication logic within the Gitea API handler. When processing authentication requests, the code path differs based on whether the username lookup succeeds before password validation occurs. This creates observable timing and response differences that leak information about account existence.

The fix implemented in Gitea Pull Request #36002 normalizes the error responses to ensure consistent behavior regardless of whether the username exists, preventing attackers from inferring valid accounts.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by sending HTTP requests to the /api/v1/user endpoint with different username values and analyzing the responses.

The attacker iterates through a list of potential usernames while monitoring response codes, response times, and message content. Differences in these responses reveal which usernames correspond to actual accounts in the Gitea instance. Once valid usernames are identified, attackers can conduct password spraying attacks, credential stuffing using credentials from data breaches, or craft targeted spear-phishing emails to compromise specific accounts.

Detection Methods for CVE-2025-69413

Indicators of Compromise

• Unusual volume of failed authentication attempts to /api/v1/user from single IP addresses
• Sequential or patterned username attempts indicating dictionary-based enumeration
• Rapid succession of API requests with varying usernames but consistent malformed credentials
• Authentication logs showing requests for non-existent users interspersed with real usernames

Detection Strategies

• Monitor API access logs for high-frequency requests to the /api/v1/user endpoint from individual sources
• Implement rate limiting detection to identify clients exceeding normal authentication attempt thresholds
• Analyze authentication failure patterns for enumeration signatures such as alphabetical or dictionary-ordered attempts
• Deploy web application firewall (WAF) rules to detect and block automated username harvesting patterns

Monitoring Recommendations

• Enable detailed API request logging including response codes, timing, and client identifiers
• Configure alerting thresholds for authentication failures per source IP within defined time windows
• Integrate Gitea logs with SIEM solutions for correlation with other reconnaissance indicators
• Establish baseline metrics for normal API authentication patterns to identify anomalies

How to Mitigate CVE-2025-69413

Immediate Actions Required

• Upgrade Gitea to version 1.25.2 or later immediately
• Review API access logs for signs of prior enumeration attempts
• Implement rate limiting on authentication endpoints if not already configured
• Consider requiring additional authentication factors for sensitive accounts

Patch Information

The vulnerability is addressed in Gitea version 1.25.2. The fix normalizes API responses for authentication failures to prevent username enumeration. Details of the patch are available in Gitea Pull Request #36002 and the official Gitea Release Announcement 1.25.2.

Organizations should upgrade to the patched version by downloading from the Gitea Release Tag v1.25.2.

Workarounds

• Implement IP-based rate limiting on the /api/v1/user endpoint to slow enumeration attempts
• Deploy a reverse proxy or WAF with rules to detect and block enumeration patterns
• Restrict API access to trusted networks or require VPN for external access where feasible
• Consider disabling public API access if not required for your deployment

# Example: Rate limiting configuration for nginx reverse proxy
# Add to nginx server block for Gitea
location /api/v1/user {
    limit_req zone=auth_limit burst=5 nodelay;
    limit_req_status 429;
    proxy_pass http://gitea_backend;
}