Discourse Calendar adds the ability to create a dynamic calendar in the first post of a topic on Discourse. Uninvited users are able to gain access to private events by crafting a request to update their attendance. This problem is resolved in commit dfc4fa15f340189f177a1d1ab2cc94ffed3c1190. As a workaround, one may use post visibility to limit access.

Discourse is an open-source discussion platform. In versions prior to 2026.1.4, 2026.3.1, 2026.4.1 and 2026.5.0-latest.1, a vulnerability in the discourse-subscriptions plugin allows users to gain access to subscription-gated groups without completing payment. This issue has been fixed in versions 2026.1.4, 2026.3.1, 2026.4.1 and 2026.5.0-latest.1.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an attacker can grant access to a private message topic through invites even after they lose access to that PM. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, unauthenticated users can determine whether a specific user is a member of a private group by observing changes in directory results when using the `exclude_groups` parameter. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, disable public access to the user directory via Admin → Settings → hide user profiles from public.

Discourse is an open-source discussion platform. In versions prior to 2026.1.4, 2026.3.1, 2026.4.1 and 2026.5.0-latest.1, an authenticated user on a Discourse instance with the form templates feature enabled can read the name and structured content of form templates that are intended exclusively for categories they are not authorized to access. Impact is limited to disclosure of site configuration metadata. This issue has been fixed in versions 2026.1.4, 2026.3.1, 2026.4.1 and 2026.5.0-latest.1.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, there is an Insecure Direct Object Reference (IDOR) vulnerability that allows any authenticated user to access metadata about AI personas, features, and LLM models by providing their identifiers. This information includes credit allocations and usage statistics which are not intended to be public. The attack is performed over the network, requires low privileges (any logged-in user), and results in a low impact on confidentiality with no impact on integrity or availability. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. To work around this issue, disable AI plugin or upgrade to a patched version.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an authorization bypass in the poll plugin allowed authenticated users to vote on, remove votes from, or toggle the open/closed status of polls they did not have access to. By passing post_id as an array (e.g. post_id[]=&post_id[]=), the authorization check resolves to the accessible post while the poll lookup resolves to a different post's poll. This affects the vote, remove_vote, and toggle_status endpoints in DiscoursePoll::PollsController. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, requesting /posts/:id.json?version=X bypassed authorization checks on post revisions. The display_post method called post.revert_to directly without verifying whether the revision was hidden or if the user had permission to view edit history. This meant hidden revisions (intentionally concealed by staff) could be read by any user by simply enumerating version numbers. Starting in versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, Discourse looks up the PostRevision and call guardian.ensure_can_see! before reverting, consistent with how the /posts/:id/revisions/:revision endpoint already authorizes access. No known workarounds are available.

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, the voters endpoint in the poll plugin lacked post visibility checks which allowed unauthorized access to voters details of polls in any post. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

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.

Discourse is an open source platform for community discussion. In affected versions users who disable chat in preferences could still be reachable in some cases. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade should disable the chat plugin within site settings.

Discourse is an open source platform for community discussion. In affected versions with some combinations of plugins, and with CSP disabled, activity streams in the user's profile page may be vulnerable to XSS. This has been patched in the latest version of Discourse core. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled.

Discourse is an open source platform for community discussion. Sites that are using discourse connect but still have local logins enabled could allow attackers to bypass discourse connect to create accounts and login. This problem is patched in the latest version of Discourse. Users unable to upgrade who are using discourse connect may disable all other login methods as a workaround.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, an authenticated moderator-level user could retrieve post content, topic titles, and usernames from categories they were not authorized to view. Insufficient access controls on a sentiment analytics endpoint allowed category permission boundaries to be bypassed. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a restriction bypass allows restricted post action counts to be disclosed to non-privileged users through a carefully crafted request. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Discourse is an open source platform for community discussion. Users can see topics with a hidden tag if they know the label/name of that tag. This issue has been patched in the latest stable, beta and tests-passed version of Discourse. All users area are advised to upgrade. There are no known workarounds for this vulnerability.

Discourse is an open source discussion platform. In versions prior to 2.7.7 there are two bugs which led to the post creator of a whisper post being revealed to non-staff users. 1: Staff users that creates a whisper post in a personal message is revealed to non-staff participants of the personal message even though the whisper post cannot be seen by them. 2: When a whisper post is before the last post in a post stream, deleting the last post will result in the creator of the whisper post to be revealed to non-staff users as the last poster of the topic.

Discourse is an open source discussion platform. Versions prior to 2.7.13 in `stable`, 2.8.0.beta11 in `beta`, and 2.8.0.beta11 in `tests-passed` allow some users to log in to a community before they should be able to do so. A user invited via email to a forum with `must_approve_users` enabled is going to be automatically logged in, bypassing the check that does not allow unapproved users to sign in. They will be able to do everything an approved user can do. If they logout, they cannot log back in. This issue is patched in the `stable` version 2.7.13, `beta` version 2.8.0.beta11, and `tests-passed` version 2.8.0.beta11. One may disable invites as a workaround. Administrators can increase `min_trust_level_to_allow_invite` to reduce the attack surface to more trusted users.

Discourse is an open source discussion platform. Prior to versions 3.5.3, 2025.11.1, and 2025.12.0, an attacker who knows part of a username can find the user and their full name via UI or API, even when `enable_names` is disabled. Versions 3.5.3, 2025.11.1, and 2025.12.0 contain a fix.

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.

Discourse is an open-source platform for community discussion. In Discourse before versions 2.7.8 and 2.8.0.beta5, a user's read state for a topic such as the last read post number and the notification level is exposed.

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups could leak to anonymous and unauthorized users through category and group endpoints. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, the MessageBus.publish call for /web_hook_events/<id> in Jobs::RedeliverWebHookEvents did not pass group_ids, leaving the channel readable by any authenticated user (or anonymous user on instances where login_required is disabled). Webhook IDs are sequential integers and trivially enumerable. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, secure uploads could be exposed by pull_hotlinked_images when an attacker knew the secured upload URL and the secure_uploads site setting was enabled. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, moderators could export CSV data for admin-restricted reports, bypassing the report visibility restrictions. This could expose sensitive operational data intended only for admins. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the `/private-posts` endpoint did not apply post-type visibility filtering, allowing regular PM participants to see whisper posts in PM topics they had access to. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the Post Edits admin report (/admin/reports/post_edits) leaked the first 40 characters of raw post content from private messages and secure categories to moderators who shouldn't have access. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, `posts_nearby` was checking topic access but then returning all posts regardless of type, including whispers that should only be visible to whisperers. Use `Post.secured(guardian)` to properly filter post types based on user permissions. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, permalinks pointing to access-restricted resources (private topics, categories, posts, or hidden tags) were redirecting users to URLs containing the resource slug, even when the user didn't have access to view the resource. This leaked potentially sensitive information (e.g., private topic titles) via the redirect Location header and the 404 page's search box. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. No known workarounds are available.

Discourse is the an open source discussion platform. In some rare cases users redeeming an invitation can be added as a participant to several private message topics that they should not be added to. They are not notified of this, it happens transparently in the background. This issue has been resolved in commit `a414520742` and will be included in future releases. Users are advised to upgrade. Users are also advised to set `SiteSetting.max_invites_per_day` to 0 until the patch is installed.

Discourse is an open source platform for community discussion. Prior to version 3.1.3 of the `stable` branch and version 3.2.0.beta3 of the `beta` and `tests-passed` branches, there is an edge case where a bookmark reminder is sent and an unread notification is generated, but the underlying bookmarkable (e.g. post, topic, chat message) security has changed, making it so the user can no longer access the underlying resource. As of version 3.1.3 of the `stable` branch and version 3.2.0.beta3 of the `beta` and `tests-passed` branches, bookmark reminders are now no longer sent if the user does not have access to the underlying bookmarkable, and also the unread bookmark notifications are always filtered by access. There are no known workarounds.

Discourse is an open source platform for community discussion. New chat messages can be read by making an unauthenticated POST request to MessageBus. This issue is patched in the 3.1.1 stable and 3.2.0.beta2 versions of Discourse. Users are advised to upgrade. There are no known workarounds for this vulnerability.

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.

In version 2.9.0.beta14 of Discourse, an open-source discussion platform, maliciously embedded urls can leak an admin's digest of recent topics, possibly exposing private information. A patch is available for version 2.9.0.beta15. There are no known workarounds for this issue.

Discourse is an open source platform for community discussion. PM titles and metadata can be read by other users when the "PM tags allowed for groups" option is enabled, the other user is a member of a group added to this option, and the PM has been tagged. This issue has been patched in the latest `stable`, `beta` and `tests-passed` versions of Discourse. Users are advised to upgrade. Users unable to upgrade should remove all groups from the the "PM tags allowed for groups" option.

Discourse is an open source platform for community discussion. This vulnerability only impacts Discourse instances configured to use `FileStore::LocalStore` which means uploads and backups are stored locally on disk. If an attacker knows the name of the Discourse backup file, the attacker can trick nginx into sending the Discourse backup file with a well crafted request. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to upgrade. Users unable to upgrade can either 1. Download all local backups on to another storage device, disable the `enable_backups` site setting and delete all backups until the site has been upgraded to pull in the fix. Or 2. Change the `backup_location` site setting to `s3` so that backups are stored and downloaded directly from S3.

Discourse is an open source platform for community discussion. Moderators can see the Screened emails list in the admin dashboard, and through that can learn the email of a user. This problem is patched in the latest version of Discourse. Users unable to upgrade should remove moderator role from untrusted users.

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a user could access another user's private activity due to insufficient authorization checks in the user actions endpoint. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch.

Discourse is an open-source community platform. A data leak vulnerability affects sites deployed between commits 10df7fdee060d44accdee7679d66d778d1136510 and 82d84af6b0efbd9fa2aeec3e91ce7be1a768511b. On login-required sites, the leak meant that some content on the site's homepage could be visible to unauthenticated users. Only login-required sites that got deployed during this timeframe are affected, roughly between April 30 2025 noon EDT and May 2 2025, noon EDT. Sites on the stable branch are unaffected. Private content on an instance's homepage could be visible to unauthenticated users on login-required sites. Versions of 3.5.0.beta4 after commit 82d84af6b0efbd9fa2aeec3e91ce7be1a768511b are not vulnerable to the issue. No workarounds are available. Sites must upgrade to a non-vulnerable version of Discourse.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, group owners who are not necessarily admins or moderators can view a group's outgoing email/SMTP credentials in plaintext via the group history log (/groups/:name/logs.json). Affected fields: email_password, email_username, smtp_server, smtp_port, smtp_ssl_mode. The most sensitive item is the SMTP password, which an owner could use to send mail as the group from outside Discourse. This impacts sites that have configured per-group SMTP credentials and granted group ownership to users who should not have access to those credentials. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, chat events for public category channels are published to MessageBus without permission scoping, so any MessageBus subscriber without chat enabled could receive chat message payloads in real time. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, an authorization bypass in the Category Chatables Controller show action allowed moderators to get information on hidden groups names and user count. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

Discourse is an open source community platform. In affected versions any user can create a topic and add arbitrary custom fields to a topic. The severity of this vulnerability depends on what plugins are installed and how the plugins uses topic custom fields. For a default Discourse installation with the default plugins, this vulnerability has no impact. The problem has been patched in the latest version of Discourse. Users are advised to update to version 3.1.1 if they are on the stable branch or 3.2.0.beta2 if they are on the beta branch. Users unable to upgrade should disable any plugins that access topic custom fields.

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.

Discourse is an open source platform for community discussion. Attackers with details specific to a poll in a topic can use the `/polls/grouped_poll_results` endpoint to view the content of options in the poll and the number of votes for groups of poll participants. This impacts private polls where the results were intended to only be viewable by authorized users. This issue is patched in the 3.1.1 stable and 3.2.0.beta2 versions of Discourse. There is no workaround for this issue apart from upgrading to the fixed version.

rails_multisite provides multi-db support for Rails applications. In affected versions this vulnerability impacts any Rails applications using `rails_multisite` alongside Rails' signed/encrypted cookies. Depending on how the application makes use of these cookies, it may be possible for an attacker to re-use cookies on different 'sites' within a multi-site Rails application. The issue has been patched in v4 of the `rails_multisite` gem. Note that this upgrade will invalidate all previous signed/encrypted cookies. The impact of this invalidation will vary based on the application architecture.

Discourse Policy plugin gives the ability to confirm users have seen or done something. Prior to version 0.1.1, if there was a policy posted to a public topic that was tied to a private group then the group members could be shown to non-group members. This issue has been patched in version 0.1.1. A workaround involves moving any policy topics with private groups to restricted categories.

The Poll Maker – Versus Polls, Anonymous Polls, Image Polls plugin for WordPress is vulnerable to Sensitive Information Exposure in versions up to and including 6.3.7. This is due to insufficient access controls on the 'ays_poll_get_user_information' AJAX action, which serializes and returns the complete WP_User object — including the user_pass (bcrypt password hash), user_email, user_login, user_registered, roles, and all capabilities — without any nonce verification or capability check beyond is_user_logged_in(). This makes it possible for authenticated attackers, with subscriber-level access and above, to retrieve sensitive account data including their own password hash, which WordPress does not expose through any of its standard interfaces and which can be leveraged for offline password-cracking attacks.

A vulnerability was identified in h2oai h2o-3 up to 7402. Affected by this issue is the function importFiles of the file h2o-core/src/main/java/water/persist/PersistNFS.java of the component ImportFile API. Such manipulation leads to information disclosure. The attack can be executed remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

MinIO is a High Performance Object Storage released under GNU Affero General Public License v3.0. `If-Modified-Since` and `If-Unmodified-Since` headers when used with anonymous requests by sending a random object name requests can be used to determine if an object exists or not on the server on a specific bucket and also gain access to some amount of information such as `Last-Modified (of the latest version)`, `Etag (of the latest version)`, `x-amz-version-id (of the latest version)`, `Expires (metadata value of the latest version)`, `Cache-Control (metadata value of the latest version)`. This conditional check was being honored before validating if the anonymous access is indeed allowed on the metadata of an object. This issue has been addressed in commit `e0fe7cc3917`. Users must upgrade to RELEASE.2024-05-27T19-17-46Z for the fix. There are no known workarounds for this issue.