CVE-2025-59833 in flagForge
Summary
by MITRE • 09/25/2025
Flag Forge is a Capture The Flag (CTF) platform. In versions from 2.1.0 to before 2.3.0, the API endpoint GET /api/problems/:id returns challenge hints in plaintext within the question object, regardless of whether the user has unlocked them via point deduction. Users can view all hints for free, undermining the business logic of the platform and reducing the integrity of the challenge system. This issue has been patched in version 2.3.0.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2025-59833 affects Flag Forge, a Capture The Flag platform designed for cybersecurity education and competition. This issue represents a critical breakdown in the platform's access control mechanisms that directly undermines its core functionality and business model. The flaw exists in versions ranging from 2.1.0 through 2.2.x, where the platform fails to properly enforce authorization checks for challenge hints, creating an arbitrary access vector that compromises the entire challenge ecosystem.
The technical implementation of this vulnerability stems from improper access control validation within the API endpoint structure. When a user makes a GET request to /api/problems/:id, the system returns complete challenge hint information within the question object without verifying whether the requesting user has earned the right to access those hints through legitimate point deduction mechanisms. This represents a classic case of inadequate input validation and access control enforcement, falling under CWE-285 which addresses insufficient authorization checks. The flaw demonstrates poor security design where the platform's business logic for hint unlocking is bypassed entirely through API manipulation.
The operational impact of this vulnerability extends far beyond simple information disclosure, fundamentally compromising the integrity of the CTF platform's competitive environment. Users can freely access all challenge hints regardless of their progress or point accumulation status, effectively neutralizing the challenge difficulty progression that the platform intends to maintain. This undermines the educational value of the platform by allowing participants to bypass the intended learning curve and problem-solving process. The vulnerability creates an unfair advantage for users who exploit the API directly, potentially leading to score manipulation and overall degradation of the competition's credibility. From an attacker's perspective, this represents a privilege escalation vulnerability that allows unauthorized access to premium content without proper authorization.
The security implications align with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1566 which addresses 'Phishing for Information'. This vulnerability enables unauthorized users to gain access to protected content through API manipulation, bypassing the platform's intended access control mechanisms. The patch implemented in version 2.3.0 addresses this by enforcing proper authorization checks before returning hint information, ensuring that users can only access hints they have legitimately earned through point deduction. Organizations should implement comprehensive access control testing and ensure that all API endpoints properly validate user permissions before returning sensitive information. The vulnerability highlights the critical importance of proper authentication and authorization validation in web applications, particularly those designed for competitive environments where maintaining integrity and fairness is paramount.