Discourse: >> Discourse >> 3.4.4 Security Vulnerabilities
Discourse is an open source discussion platform. Version before 3.6.2 and 3.6.0.beta2, default Cache-Control response header with value no-store, no-cache was missing from error responses. This may caused unintended caching of those responses by proxies potentially leading to cache poisoning attacks. This vulnerability is fixed in 3.6.2 and 3.6.0.beta2.
CVSS Score
5.3
EPSS Score
0.001
Published
2025-10-28
Discourse is an open-source community discussion platform. In versions 3.5.0 and below, malicious meta-commands could be embedded in a backup dump and executed during restore. In multisite setups, this allowed an admin of one site to access data or credentials from other sites. This issue is fixed in version 3.5.1.
CVSS Score
6.8
EPSS Score
0.001
Published
2025-10-01
Discourse is an open-source community discussion platform. Versions 3.5.0 and below are vulnerable to XSS attacks through parsing and rendering of chat channel titles and chat thread titles via the quote message functionality when using the rich text editor. This issue is fixed in version 3.5.1.
CVSS Score
3.5
EPSS Score
0.001
Published
2025-10-01
Discourse is an open-source community discussion platform. In versions 3.5.0 and below, the Discourse AI suggestion endpoints for topic “Title”, “Category”, and “Tags” allowed authenticated users to extract information about topics that they weren’t authorized to access. By modifying the “topic_id” value in API requests to the AI suggestion endpoints, users could target specific restricted topics. The AI model’s responses then disclosed information that the authenticated user couldn’t normally access. This issue is fixed in version 3.5.1. To workaround this issue, users can restrict group access to the AI helper feature through the "composer_ai_helper_allowed_groups" and "post_ai_helper_allowed_groups" site settings.
CVSS Score
4.3
EPSS Score
0.001
Published
2025-10-01
Discourse is an open-source community discussion platform. Prior to version 3.4.7 on the `stable` branch and version 3.5.0.beta.8 on the `tests-passed` branch, upon issuing a physical security key for 2FA, the server generates a WebAuthn challenge, which the client signs. The challenge is not cleared from the user’s session after authentication, potentially allowing reuse and increasing security risk. This is fixed in versions 3.4.7 and 3.5.0.beta.8.
CVSS Score
9.8
EPSS Score
0.002
Published
2025-07-29
Discourse is an open-source discussion platform. The visibility of posts typed `whisper` is controlled via the `whispers_allowed_groups` site setting. Only users that belong to groups specified in the site setting are allowed to view posts typed `whisper`. However, it has been discovered that users of versions prior to 3.4.6 on the `stable` branch and prior to 3.5.0.beta8-dev on the `tests-passed` branch can continue to see their own whispers even after losing visibility of posts typed `whisper`. This issue is patched in versions 3.4.6 and 3.5.0.beta8-dev. No known workarounds are available.
CVSS Score
7.5
EPSS Score
0.001
Published
2025-06-25
Discourse is a platform for community discussion. In affected versions any private message that includes a group had its title and participating user exposed to users that do not have access to the private messages. However, access control for the private messages was not compromised as users were not able to view the posts in the leaked private message despite seeing it in their inbox. The problematic commit was reverted around 32 minutes after it was made. Users are encouraged to upgrade to the latest commit if they are running Discourse against the `tests-passed` branch.
CVSS Score
7.5
EPSS Score
0.007
Published
2021-09-20