CVE-2022-39378 is a medium-severity vulnerability affecting Discourse, a widely used open-source platform for community discussions. The vulnerability arises from an information exposure issue (CWE-200) where, under certain conditions, a user badge awarded based on participation in a restricted-access topic inadvertently reveals the title of that topic to any user, including unauthorized actors. Specifically, if a user earns a badge linked to activity within a private or restricted topic, the badge metadata may include the topic title. Prior to the patch, this allowed any user, regardless of their access permissions, to view potentially sensitive information embedded in the topic title. This exposure could lead to unauthorized disclosure of confidential or sensitive information if such details were included in topic titles. The vulnerability affects Discourse versions up to and including 2.8.9 and 2.9.0.beta10. The issue has been addressed in the latest stable, beta, and tests-passed versions of Discourse. No known exploits have been reported in the wild, and no workarounds are currently available. The vulnerability does not require authentication to exploit, as any user can view the badge and associated topic title once the badge is awarded. However, exploitation depends on the presence of badges linked to restricted topics and the inclusion of sensitive information in topic titles, which may not be common practice but remains a risk in environments where sensitive discussions occur. The exposure impacts confidentiality but does not affect integrity or availability of the system. The scope is limited to the information leakage of topic titles via user badges, not the broader content of restricted topics or other data.

For European organizations using Discourse as a community or internal collaboration platform, this vulnerability poses a risk of unintended information disclosure. Sensitive project names, internal initiatives, or confidential discussion topics could be exposed through badge metadata, potentially leading to information leakage to unauthorized users or external actors. This could undermine trust in the platform, violate data protection policies, and expose organizations to compliance risks under regulations such as GDPR if personal or sensitive data is inadvertently disclosed. The impact is more pronounced in sectors handling sensitive or classified information, such as government, defense, finance, healthcare, and critical infrastructure. While the vulnerability does not allow direct access to restricted content, the exposure of topic titles could provide adversaries with intelligence about internal activities or priorities. Given that no authentication is required to view the exposed information, the risk extends to any user with access to the Discourse instance, including external users if the platform is publicly accessible. The absence of known exploits reduces immediate risk, but organizations should act promptly to prevent potential future exploitation.

Organizations should upgrade Discourse installations to the latest stable or beta versions where the vulnerability is patched. Since no workarounds exist, patching is the primary mitigation step. Additionally, organizations should audit existing badges and associated topic titles to identify and remove or rename any that contain sensitive information. Implementing strict content policies to avoid including sensitive data in topic titles is advisable. Access controls should be reviewed to limit badge visibility where possible, and monitoring for unusual access patterns to badges or user profiles may help detect exploitation attempts. For environments with high confidentiality requirements, consider restricting badge awards linked to restricted topics or disabling badge display temporarily until patches are applied. Regularly reviewing Discourse configurations and staying informed about updates from the vendor will help maintain security posture. Finally, educating users and administrators about the risks of embedding sensitive information in topic titles can reduce exposure.