CVE-2024-53266 in Discourse
Summary
by MITRE • 02/05/2025
Discourse is an open source platform for community discussion. In affected versions with some combinations of plugins, and with CSP disabled, activity streams in the user's profile page may be vulnerable to XSS. This has been patched in the latest version of Discourse core. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled.
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Analysis
by VulDB Data Team • 09/25/2025
CVE-2024-53266 represents a cross-site scripting vulnerability affecting the Discourse community discussion platform, which operates under CWE-79 as a classic input validation and output encoding weakness. The vulnerability manifests specifically within the activity streams displayed on user profile pages when certain plugin combinations are active alongside a disabled Content Security Policy configuration. This flaw allows attackers to inject malicious scripts that execute in the context of authenticated users' browsers, potentially enabling session hijacking, data exfiltration, or privilege escalation attacks.
The technical exploitation of this vulnerability occurs through the manipulation of user activity data that gets rendered without proper sanitization or encoding in the profile page's activity stream section. When CSP is disabled, the browser's security mechanisms that typically prevent script execution from untrusted sources are bypassed, creating a direct pathway for malicious payloads to be executed. This vulnerability is particularly concerning in community platforms where users may have varying privilege levels and where the activity streams often contain user-generated content that could be manipulated by attackers.
The operational impact of CVE-2024-53266 extends beyond simple script execution, potentially enabling attackers to perform actions as authenticated users within the Discourse environment. This includes accessing private messages, modifying user profiles, creating posts, or even escalating privileges if the compromised user has administrative capabilities. The vulnerability's exploitation requires specific conditions including the presence of certain plugin combinations and the absence of CSP, which makes it somewhat situational but still significant given that many installations may not have proper CSP configurations enabled by default.
Organizations and administrators should prioritize upgrading to the latest Discourse core version to address this vulnerability, as the patch resolves the underlying issue through proper input sanitization and output encoding mechanisms. For environments where immediate upgrades are not feasible, enabling Content Security Policy represents the primary mitigation strategy, which aligns with the ATT&CK framework's defensive techniques for preventing code injection vulnerabilities. Additionally, implementing proper input validation for user-generated content, regular security audits of installed plugins, and monitoring for unusual activity patterns can further reduce the risk exposure associated with this vulnerability. The vulnerability demonstrates the importance of maintaining secure default configurations and the critical role that security headers like CSP play in protecting web applications from client-side attacks.