CVE-2025-59826 is a high-severity vulnerability identified in Flag Forge, a Capture The Flag (CTF) platform widely used for cybersecurity training and competitions. The vulnerability exists in version 2.1.0 of the software and is classified under CWE-862, which denotes missing authorization. Specifically, non-administrative users are able to create arbitrary challenges within the platform without proper authorization checks. This flaw allows unauthorized users to introduce malicious, incorrect, or misleading content into the challenge repository. Such unauthorized challenge creation can undermine the integrity of the platform by confusing participants, distributing harmful payloads, or manipulating scoring systems. The vulnerability has a CVSS v3.1 base score of 7.6, indicating a high severity level. The vector metrics show that the attack can be performed remotely over the network (AV:N) with low attack complexity (AC:L), requiring only privileges of a non-admin user (PR:L) and no user interaction (UI:N). The impact scope is unchanged (S:U), with low confidentiality impact (C:L), high integrity impact (I:H), and low availability impact (A:L). The vulnerability was patched in version 2.2.0 of Flag Forge, and no known exploits are currently reported in the wild. The root cause is a missing authorization check that should restrict challenge creation capabilities to admin users only. This flaw can be exploited by any authenticated non-admin user, making it a significant risk in environments where multiple users have access to the platform.

For European organizations using Flag Forge 2.1.0, particularly educational institutions, cybersecurity training centers, and companies running internal CTF competitions, this vulnerability poses a substantial risk. Unauthorized creation of challenges can lead to the insertion of malicious content that may execute harmful code on participants' systems or mislead users, degrading the quality and trustworthiness of training exercises. This can result in compromised learning outcomes, potential exposure to malware, and reputational damage. Additionally, the integrity of scoring and competition fairness can be compromised, affecting organizational trust in the platform. Since the vulnerability requires only low-level user privileges, insider threats or compromised user accounts can easily exploit it. The low confidentiality impact suggests limited direct data leakage, but the high integrity impact means that the platform's content and results can be manipulated. Availability impact is low but could increase if malicious challenges cause platform instability. Given the collaborative and competitive nature of CTF platforms, this vulnerability could disrupt training programs and reduce confidence in cybersecurity readiness initiatives across European organizations.

European organizations should immediately upgrade Flag Forge installations from version 2.1.0 to version 2.2.0 or later, where the authorization checks have been properly implemented. Until the upgrade is applied, administrators should restrict platform access to trusted users only and monitor challenge creation activities closely. Implement role-based access controls (RBAC) to ensure only authorized admin users can create or modify challenges. Conduct audits of existing challenges to identify and remove any unauthorized or suspicious content. Additionally, organizations should enforce strong authentication mechanisms to reduce the risk of account compromise. Network segmentation and monitoring of Flag Forge traffic can help detect anomalous behavior indicative of exploitation attempts. Training platform administrators on secure configuration and timely patch management is critical. Finally, organizations should consider deploying web application firewalls (WAFs) with custom rules to detect and block unauthorized challenge creation attempts if immediate patching is not feasible.