CVE-2022-36057 is a vulnerability identified in the discourse-chat plugin, an asynchronous messaging extension for the Discourse open-source discussion platform. The vulnerability is categorized as CWE-80 and CWE-79, which relate to improper neutralization of script-related HTML tags and improper input neutralization during web page generation, respectively. Specifically, this vulnerability allows Cross-Site Scripting (XSS) attacks due to insufficient sanitization of HTML content inserted by admin users into chat titles and descriptions. When an admin user inputs malicious HTML or script code into these fields, the code can be executed in the browsers of other users viewing the chat, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim user. The issue affects versions of discourse-chat prior to 0.9, with version 0.9 containing a patch that addresses this vulnerability. Notably, exploitation requires admin privileges to insert the malicious content, but no user interaction beyond viewing the affected chat content is necessary for the attack to succeed. There are no known exploits in the wild reported to date. The vulnerability was publicly disclosed on September 6, 2022, and has been enriched by CISA, indicating its recognized importance in cybersecurity circles. The nature of the vulnerability is typical of reflected or stored XSS attacks, where malicious scripts are injected into web pages and executed in the context of other users' browsers, compromising confidentiality and integrity of user data and potentially impacting availability if leveraged for denial-of-service attacks.

For European organizations using the Discourse platform with the discourse-chat plugin (versions prior to 0.9), this vulnerability poses a moderate risk. The primary impact is on confidentiality and integrity, as attackers with admin access can inject malicious scripts that execute in other users' browsers, potentially stealing session cookies, personal data, or performing unauthorized actions. This can lead to reputational damage, data breaches, and compliance violations under regulations such as GDPR. The availability impact is generally low unless the XSS is leveraged in a way that disrupts service. Since exploitation requires admin privileges, the threat is somewhat mitigated by internal access controls; however, insider threats or compromised admin accounts could facilitate attacks. European organizations with active community forums or internal collaboration platforms using Discourse-chat are at risk of targeted attacks aiming to escalate privileges or harvest sensitive information. The vulnerability could also be exploited in social engineering campaigns to deliver malicious payloads. Given the widespread use of Discourse in various sectors including education, government, and private enterprises across Europe, the potential impact is significant but contained by the requirement for admin-level access to inject malicious content.

1. Immediate upgrade of discourse-chat plugin to version 0.9 or later, which contains the official patch addressing this XSS vulnerability. 2. Implement strict role-based access controls (RBAC) to limit admin privileges only to trusted personnel and regularly review admin accounts for anomalies. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts within the Discourse platform, reducing the impact of potential XSS payloads. 4. Conduct regular security audits and code reviews of any custom plugins or modifications to Discourse to ensure no similar injection flaws exist. 5. Enable and monitor logging for admin actions within Discourse to detect suspicious insertions of HTML or script content. 6. Educate administrators on the risks of inserting untrusted HTML content and enforce input validation and sanitization policies even for privileged users. 7. Where feasible, isolate Discourse instances behind web application firewalls (WAFs) configured to detect and block XSS attack patterns. 8. Regularly update and patch the entire Discourse platform and its plugins to minimize exposure to known vulnerabilities.