CVE-2025-54528: JetBrains TeamCity CSRF Vulnerability

CVE-2025-54528 Overview

A Cross-Site Request Forgery (CSRF) vulnerability has been identified in JetBrains TeamCity versions prior to 2025.07. This security flaw exists within the GitHub App connection flow, allowing attackers to potentially perform unauthorized actions on behalf of authenticated users. CSRF vulnerabilities enable malicious actors to trick users into executing unwanted actions on web applications where they are currently authenticated.

Critical Impact

Attackers can exploit this CSRF vulnerability to manipulate GitHub App connections in TeamCity, potentially leading to unauthorized access to source code repositories, CI/CD pipeline modifications, and compromise of the software development lifecycle.

Affected Products

• JetBrains TeamCity versions prior to 2025.07
• TeamCity instances with GitHub App integration configured
• Self-hosted and cloud-based TeamCity deployments using GitHub connections

Discovery Timeline

• 2025-07-28 - CVE-2025-54528 published to NVD
• 2025-07-31 - Last updated in NVD database

Technical Details for CVE-2025-54528

Vulnerability Analysis

This Cross-Site Request Forgery vulnerability (CWE-352) affects the GitHub App connection flow in JetBrains TeamCity. The vulnerability stems from insufficient anti-CSRF token validation during the OAuth-style connection process between TeamCity and GitHub Apps. When a user initiates or manages GitHub App connections, the application fails to properly verify that requests originate from the legitimate user session.

An attacker could craft a malicious web page or email containing hidden requests targeting the GitHub App connection endpoints. When an authenticated TeamCity administrator visits the attacker-controlled content, their browser automatically includes valid session credentials, allowing the attacker to modify GitHub App configurations, establish unauthorized connections, or disconnect existing integrations without user consent.

Root Cause

The root cause of CVE-2025-54528 lies in the absence or improper implementation of CSRF protection mechanisms within the GitHub App connection workflow. Specifically, the application does not adequately validate state tokens or anti-forgery tokens during critical connection operations. This allows forged cross-origin requests to be processed as legitimate user actions when the victim has an active TeamCity session.

Attack Vector

The attack vector for this vulnerability is network-based and requires user interaction. An attacker must lure an authenticated TeamCity user to visit a malicious webpage or click a crafted link. The attack does not require any privileges on the target system, but the attacker must have knowledge of the target TeamCity instance URL. The vulnerability affects confidentiality, integrity, and availability of the system by potentially allowing unauthorized manipulation of source code connections and CI/CD configurations.

The exploitation flow typically involves:

1. Attacker identifies a target TeamCity instance with GitHub App integration
2. Attacker crafts a malicious page containing forged requests to GitHub App connection endpoints
3. Victim with active TeamCity session visits the malicious page
4. Victim's browser sends authenticated requests to TeamCity
5. TeamCity processes the forged requests as legitimate, modifying GitHub App configurations

Detection Methods for CVE-2025-54528

Indicators of Compromise

• Unexpected changes to GitHub App connection configurations in TeamCity
• New or modified GitHub App integrations that administrators did not authorize
• Audit log entries showing GitHub connection changes without corresponding administrative actions
• Unusual OAuth callback requests in web server logs from external referrers

Detection Strategies

• Monitor TeamCity audit logs for GitHub App connection modifications and correlate with administrator activity
• Implement web application firewall rules to detect cross-origin requests to GitHub App endpoints
• Review HTTP referer headers for requests to sensitive TeamCity configuration endpoints
• Configure alerting for any changes to source control integrations outside of change windows

Monitoring Recommendations

• Enable verbose logging for all TeamCity administration actions, particularly VCS and connection management
• Establish baseline patterns for GitHub App connection activity and alert on deviations
• Monitor for external referrer sources in requests to TeamCity administrative endpoints
• Implement network segmentation to restrict access to TeamCity administration interfaces

How to Mitigate CVE-2025-54528

Immediate Actions Required

• Upgrade JetBrains TeamCity to version 2025.07 or later immediately
• Review all existing GitHub App connections for unauthorized modifications
• Audit TeamCity access logs for suspicious activity patterns around GitHub integrations
• Restrict administrative access to TeamCity through network controls until patching is complete

Patch Information

JetBrains has addressed this vulnerability in TeamCity version 2025.07. Organizations should upgrade to this version or later to remediate CVE-2025-54528. The official security advisory and patch information is available through the JetBrains Security Issues Fixed page. Apply the update following standard change management procedures, ensuring proper backup of TeamCity configurations before upgrading.

Workarounds

• Temporarily disable GitHub App connections if immediate patching is not feasible
• Implement strict Content Security Policy headers to limit cross-origin request capabilities
• Require re-authentication for sensitive GitHub App connection operations
• Use network-level access controls to limit who can access TeamCity administration interfaces

# Configuration example - Restrict TeamCity admin access via reverse proxy
# nginx configuration to limit administration access by IP
location /admin/integrations/github/ {
    allow 10.0.0.0/8;
    allow 192.168.1.0/24;
    deny all;
    
    # Add additional CSRF protection headers
    add_header X-Frame-Options "DENY";
    add_header X-Content-Type-Options "nosniff";
    add_header Referrer-Policy "strict-origin-when-cross-origin";
}