CVE-2022-46150 is a medium-severity vulnerability affecting Discourse, an open-source discussion platform widely used for online forums and community engagement. The vulnerability pertains to an information disclosure issue classified under CWE-200, where unauthorized users can infer the existence of hidden tags and confirm their application to topics they have access to. Specifically, versions prior to 2.8.13 on the stable branch and versions from 2.9.0.beta0 up to but not including 2.9.0.beta14 on the beta and tests-passed branches are affected. Hidden tags in Discourse are typically used to categorize or moderate content discreetly, and their exposure could reveal sensitive organizational or community moderation practices, potentially undermining confidentiality and trust. The flaw does not allow direct access to the content of the hidden tags but leaks metadata about their presence and application, which can be leveraged for reconnaissance by unauthorized actors. The issue is resolved in Discourse version 2.8.13 (stable) and 2.9.0.beta14 (beta and tests-passed). As an interim mitigation, administrators can disable all emails to non-staff users via the 'disable_email' site setting, reducing the risk of information leakage through email notifications. There are no known exploits in the wild, and the vulnerability requires no authentication beyond what is normally granted to users with access to the topics, meaning that any user with topic access but without elevated privileges can exploit this information leak. The impact is primarily on confidentiality, with limited effect on integrity or availability.

For European organizations using Discourse as a platform for internal or external communications, this vulnerability could lead to unintended disclosure of sensitive metadata about content categorization and moderation. This exposure might allow malicious actors or competitors to infer internal processes, moderation policies, or sensitive project discussions, potentially compromising organizational confidentiality and strategic information. While the vulnerability does not directly expose content or allow system compromise, the leakage of hidden tag existence could facilitate targeted social engineering or reconnaissance attacks. Organizations in sectors with strict data privacy requirements, such as finance, healthcare, or government, may face compliance risks if sensitive operational details are inferred through this vulnerability. Additionally, community-driven platforms in Europe that rely on Discourse for member engagement could suffer reputational damage if users perceive a lack of confidentiality. The overall operational impact is moderate, but the risk to confidentiality and trust is significant enough to warrant prompt remediation.

1. Upgrade Discourse installations to version 2.8.13 (stable) or 2.9.0.beta14 (beta/tests-passed) or later to apply the official patch addressing this vulnerability. 2. Until patching is possible, enable the 'disable_email' site setting to prevent emails being sent to non-staff users, thereby reducing the risk of sensitive information leakage through email notifications. 3. Review and audit user permissions to ensure that only necessary users have access to topics where hidden tags are applied, minimizing the exposure surface. 4. Monitor Discourse logs for unusual access patterns or attempts to enumerate tags or topics, which could indicate reconnaissance activity. 5. Educate community moderators and administrators about the sensitivity of tag usage and encourage cautious application of hidden tags to sensitive topics. 6. Consider implementing additional access controls or content segmentation for highly sensitive discussions to mitigate risks from metadata exposure. 7. Stay informed about Discourse security updates and subscribe to vendor advisories to promptly address any future related vulnerabilities.