CVE-2025-3636 is an authorization bypass vulnerability identified in multiple recent versions of Moodle, a widely used open-source learning management system. The vulnerability stems from insufficient capability checks on user-controlled keys that gate access to RSS feeds within the platform. Specifically, unauthorized users with low-level privileges can exploit this flaw to access and view RSS feeds that should be restricted, bypassing normal authorization mechanisms. The vulnerability is remotely exploitable over the network without requiring user interaction, and only low privileges are needed to trigger the flaw. The primary impact is confidentiality loss, as unauthorized users can view potentially sensitive course or user information exposed via RSS feeds. There is no impact on data integrity or system availability. The CVSS v3.1 base score is 4.3 (medium), reflecting the ease of network exploitation with low privileges but limited impact scope. No known public exploits or patches have been reported as of the publication date. The vulnerability affects Moodle versions 4.1.0, 4.3.0, 4.4.0, and 4.5.0, which are widely deployed in educational institutions globally. The root cause is inadequate validation of user capabilities controlling access to RSS feed content, allowing unauthorized access through crafted requests. This flaw highlights the importance of rigorous access control enforcement in web applications handling sensitive educational data.

The primary impact of CVE-2025-3636 is unauthorized disclosure of information via RSS feeds in Moodle, potentially exposing sensitive educational content or user data to unauthorized parties. This confidentiality breach could lead to privacy violations, leakage of course materials, or exposure of user activity information. While the vulnerability does not affect data integrity or availability, the unauthorized access could undermine trust in the affected educational platforms and lead to compliance issues with data protection regulations. Organizations relying on Moodle for critical educational services may face reputational damage if sensitive information is leaked. Since exploitation requires only low privileges and no user interaction, attackers with minimal access could leverage this flaw to gather intelligence or conduct further attacks. However, the absence of known exploits in the wild and the medium CVSS score suggest a moderate risk level at present. The scope is limited to affected Moodle versions, but given Moodle's global adoption, the potential impact spans multiple sectors and countries.

To mitigate CVE-2025-3636, organizations should immediately audit and restrict access controls related to RSS feed generation and consumption within Moodle. Administrators should verify that capability checks are correctly enforced and that RSS feeds do not expose sensitive information to unauthorized users. Until official patches are released, consider disabling RSS feed functionality or restricting it to trusted users only. Monitor Moodle security advisories and apply vendor patches promptly once available. Employ network segmentation and access controls to limit exposure of Moodle instances to untrusted networks. Additionally, implement logging and alerting on unusual access patterns to RSS feeds to detect potential exploitation attempts. Educate administrators and users about the risk of unauthorized data exposure through RSS feeds. Regularly update Moodle installations to the latest secure versions and conduct security reviews focusing on authorization mechanisms. If custom plugins or integrations interact with RSS feeds, review their code for similar authorization weaknesses.