CVE-2025-59841 in flagForge
Summary
by MITRE • 09/25/2025
Flag Forge is a Capture The Flag (CTF) platform. In versions from 2.2.0 to before 2.3.1, the FlagForge web application improperly handles session invalidation. Authenticated users can continue to access protected endpoints, such as /api/profile, even after logging out. CSRF tokens are also still valid post-logout, which can allow unauthorized actions. This issue has been patched in version 2.3.1.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2025-59841 affects Flag Forge, a Capture The Flag platform that serves as a web-based environment for cybersecurity competitions and training exercises. This authentication and session management flaw represents a critical security weakness in the application's access control mechanisms, potentially compromising the integrity of CTF environments where users engage in legitimate security testing activities. The vulnerability exists within versions ranging from 2.2.0 through the pre-release of 2.3.1, indicating a regression or oversight in session handling that persisted across multiple releases before being addressed.
The core technical flaw involves improper session invalidation mechanisms within the Flag Forge application. When authenticated users log out of the system, the application fails to properly terminate their sessions and invalidate associated CSRF tokens. This creates a persistent access vector where users can continue to make authenticated requests to protected endpoints such as /api/profile and other sensitive resources. The vulnerability stems from inadequate session cleanup processes that leave active session identifiers and security tokens in memory or storage, allowing attackers to reuse these credentials for unauthorized access. This behavior violates fundamental security principles of proper session termination and access revocation.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it creates persistent security risks within CTF environments where users may be conducting legitimate penetration testing activities. Attackers who gain access to a user's session token or CSRF token can continue to perform actions on behalf of the authenticated user even after logout, potentially compromising the integrity of competition data, user profiles, and other sensitive information. The continued validity of CSRF tokens post-logout specifically enables attackers to perform unauthorized actions through cross-site request forgery attacks, where malicious actors could manipulate the application to perform unintended operations. This vulnerability undermines the trust model of the platform and creates potential attack vectors that could be exploited in both legitimate and malicious contexts.
The security implications of this vulnerability align with CWE-613, which addresses "Insufficient Session Expiration" and CWE-352, covering Cross-Site Request Forgery. The attack pattern follows typical privilege escalation and session hijacking techniques documented in the MITRE ATT&CK framework under T1548.001 for Abuse of System-Level Privileges and T1566 for Phishing. Organizations using Flag Forge should immediately implement the patch available in version 2.3.1, which properly invalidates sessions and CSRF tokens upon user logout. Additional mitigations include implementing robust session management policies, regular session cleanup processes, and monitoring for unauthorized access attempts. Security teams should also consider conducting thorough access control reviews and implementing session timeout mechanisms to prevent similar issues in other applications within their infrastructure. The vulnerability demonstrates the critical importance of proper session lifecycle management in web applications, particularly those handling sensitive user data and authentication contexts.