CVE-2022-21678 is a medium-severity vulnerability affecting Discourse, an open-source discussion platform widely used for online community forums and collaboration. The vulnerability pertains to an exposure of sensitive information (CWE-200) where user bios intended to be private were inadvertently exposed in the HTML <meta> tags on user profile pages. This issue affects Discourse versions prior to 2.7.13 in the stable branch and prior to 2.8.0.beta11 in the beta and tests-passed branches. Specifically, even when users set their profiles to private, their bios remained visible in the page metadata, which is accessible to any visitor or automated crawler without authentication or user interaction. This exposure could allow unauthorized actors to harvest personal or sensitive information about users, potentially leading to privacy violations or targeted social engineering attacks. The vulnerability was patched in Discourse versions 2.7.13 (stable) and 2.8.0.beta11 (beta and tests-passed branches). There are no known exploits in the wild, and the issue was publicly disclosed in January 2022. The root cause is a failure to properly restrict sensitive user data in the metadata rendering logic of user profile pages, resulting in unintended data leakage despite privacy settings. This vulnerability does not directly impact system integrity or availability but compromises confidentiality of user data. Exploitation requires no authentication or user interaction, making it trivially accessible to any visitor or automated tool scanning Discourse forums running vulnerable versions.

For European organizations using Discourse as a community or collaboration platform, this vulnerability poses a privacy risk by exposing user bios that were intended to be private. This could lead to unauthorized disclosure of personal or sensitive information, potentially violating GDPR and other privacy regulations applicable in Europe. The exposure could facilitate targeted phishing or social engineering attacks against users, undermining trust in the platform and the organization. While the vulnerability does not affect system availability or integrity, the confidentiality breach could damage organizational reputation and lead to regulatory penalties if personal data is mishandled. Organizations operating forums with sensitive user communities, such as healthcare, finance, or governmental sectors, may face heightened risks. Additionally, the ease of access to this data without authentication increases the likelihood of automated data harvesting by malicious actors. Given the widespread use of Discourse in European tech, academic, and public sectors, the impact is non-negligible but limited to information disclosure rather than system compromise.

1. Immediate upgrade of Discourse installations to version 2.7.13 (stable) or 2.8.0.beta11 (beta/tests-passed) or later, where the vulnerability is patched. 2. Review and audit user profile privacy settings and metadata rendering configurations to ensure no sensitive information is exposed inadvertently. 3. Implement web application firewall (WAF) rules to monitor and potentially block suspicious automated scraping of user profile pages. 4. Conduct user awareness campaigns to inform users about the privacy settings and encourage minimal sharing of sensitive information in bios. 5. For organizations unable to upgrade immediately, consider temporarily disabling user bios or restricting profile page access via authentication or IP whitelisting. 6. Monitor public forums and threat intelligence sources for any emerging exploits or scanning activity targeting Discourse instances. 7. Ensure compliance with GDPR by documenting the exposure incident and mitigation steps, and notify affected users if necessary. 8. Regularly review Discourse release notes and security advisories for timely patching of future vulnerabilities.