Overview
The cybersecurity landscape is constantly evolving, and as new threats emerge, it remains crucial for organizations to stay vigilant. In this regard, one recent vulnerability that has caught the attention of cybersecurity professionals is CVE-2025-59841. This vulnerability affects the Flag Forge Capture The Flag (CTF) platform, which is widely used by cybersecurity teams for training and skill development purposes.
The vulnerability stems from Flag Forge’s web application’s improper handling of session invalidation in versions 2.2.0 to before 2.3.1. This flaw could potentially lead to system compromise or data leakage, posing a significant threat to organizations that rely on Flag Forge for their cybersecurity training.
Vulnerability Summary
CVE ID: CVE-2025-59841
Severity: Critical (9.8 CVSS Severity Score)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise or data leakage
Affected Products
Escape the Surveillance Era
Most apps won’t tell you the truth.
They’re part of the problem.
Phone numbers. Emails. Profiles. Logs.
It’s all fuel for surveillance.
Ameeba Chat gives you a way out.
- • No phone number
- • No email
- • No personal info
- • Anonymous aliases
- • End-to-end encrypted
Chat without a trace.
Product | Affected Versions
Flag Forge | 2.2.0 to 2.3.0
How the Exploit Works
The vulnerability resides in the improper handling of session invalidation by the Flag Forge web application. In a typical secure application, logging out should invalidate a user session, making it impossible for any user to continue accessing protected endpoints. However, in the affected versions of Flag Forge, authenticated users can continue to access protected endpoints such as /api/profile even after logging out.
Moreover, the Cross-Site Request Forgery (CSRF) tokens remain valid post-logout. This allows potential attackers to perform unauthorized actions since the system still recognizes these tokens as legitimate. This vulnerability opens a potential attack vector for malicious actors who can exploit this flaw to possibly compromise the system or leak sensitive data.
Conceptual Example Code
Here’s a conceptual example of how an attacker might exploit this vulnerability:
GET /api/profile HTTP/1.1
Host: target.example.com
Cookie: sessionid=...; csrftoken=...
GET /logout HTTP/1.1
Host: target.example.com
Cookie: sessionid=...; csrftoken=...
GET /api/profile HTTP/1.1
Host: target.example.com
Cookie: sessionid=...; csrftoken=...In this example, the attacker is able to access the /api/profile endpoint even after issuing a /logout request, exploiting the session invalidation vulnerability. The CSRF token remains valid after logout, allowing the attacker to continue accessing the user’s profile.
It is strongly recommended to apply the vendor patch (version 2.3.1) or use a Web Aplication Firewall (WAF) or Intrusion Detection System (IDS) as temporary mitigation. Always ensure that your systems are up-to-date with the latest security patches to protect against such vulnerabilities.
