Vendor
Discourse
323 known vulnerabilities.
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Medium 6.0
Discourse: Information Disclosure in Form Template API Due to Missing Authorization
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 te…
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Medium 5.3
Discourse: Cached outdated summaries can leak removed content
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 In versions prior to 2026.1.4, 2026.3.1, 2026.4.1 and 2026.5.0-latest.1, outdated cached AI summaries can leak removed content to anonymous and unprivileged users who cannot regenerate summaries. This issue has…
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Medium 6.3
Discourse: Hidden tag visibility bypass on tag routes
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 vulnerability allows unauthenticated or unauthorized users t…
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Medium 5.1
Discourse: Improper Access Control in discourse-ai Allows Unauthorized Category Content Exposure
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…
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Medium 5.3
Discourse: Hidden group names and access metadata are exposed to moderators through the `category-chatables` endpoint
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 mod…
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Medium 5.3
Discourse: Group SMTP test endpoint susceptible to SSRF
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, the group email settings test endpoint could be used to make the server initiate out…
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Medium 6.3
Discourse: Vulnerability in discourse-subscriptions plugin allowing users to self-grant to higher tier subscriptions
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, a user may be able to purchase a lower tier subscription but grant themselves the be…
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Medium 4.3
Discourse: Authorization bypass in oneboxer via user-controlled category id
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 user can obtain shared draft topic titles by sending an inline oneb…
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Medium 5.3
Discourse: Missing post-level authorization allows whisper metadata disclosure
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, non-staff users could access read receipt information for staff-only posts they were…
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Medium 6.3
Discourse: Insufficient topic visibility check allows unauthorized poll manipulation in private categories
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, users who lost access to a topic (e.g., removed from a private category group) could…
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Medium 4.3
Discourse: Unauthorized channel membership inference via excluded_memberships_channel_id
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, there is possible channel membership inference from chat user search without authori…
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Medium 5.3
Discourse: Category group moderators can perform actions on topics in restricted categories without read access
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, category group moderators could perform privileged actions on topics inside private …
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Medium 5.4
Discourse: XSS on category description update via API
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, updating a category description via API is not sanitizing the description string, wh…
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Medium 5.3
Discourse: Stored XSS in discourse-ai shared conversations onebox
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 attacker with the ability to create shared AI conversations could inject arbitrar…
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Medium 5.1
Discourse: Open redirect via `sso_destination_url` cookie in `enter`
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, the enter action in StaticController reads the sso_destination_url cookie and redire…
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Medium 5.3
Discourse: Admin-only report can be exported by moderators
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 …
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Medium 4.9
Discourse Allows Unauthorized Access to Deleted Posts Index via Group Membership
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a non-staff user with elevated group membership could access deleted posts belonging to any user due to an overly broad authorization check on the de…
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Medium 6.9CVE-2026-33425 Scanner template
Discourse has inferable private group membership or existence via exclude_groups parameter
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 `…
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Medium 5.9
PM access granted through invites after access revocation
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,…
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Medium 5.4
Discourse's solved topic stream has potential stored XSS in topic title
Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a potential stored XSS in topic titles for the solved posts stream. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a work…
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Medium 5.1
Discourse user can create Zendesk tickets even when it does not have access to topic
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, moderators can create Zendesk tickets for topics they do not have access to view. This affects all forums that use the Zendesk plugin. Versions 2026.…
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Medium 5.4
Discourse has a Hidden Solved topics permission bypass
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 vulnerability in hidden Solved topics may allow unauthorized users to accept or unaccept solutions. Versions 2026.3.0-latest.…
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Medium 5.3
Discourse's unscoped status lookups leak restricted metadata
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, …
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Medium 5.3
Discourse: Composer mentions endpoint leaks hidden group membership through PM `allowed_names` check
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the ComposerController#mentions endpoint reveals hidden group membership to any authenticated user who can message the group. By supplying allowed_na…
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Medium 5.3
Discourse has a poll authorization bypass via post_id array parameter
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 …
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Medium 5.3
Discourse hasUnauthorized Exposure of Private User Action Types
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…
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Medium 5.3
Discourse has Unauthorized Post Data Exposure in discourse-user-notes
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a moderator could exploit insufficient authorization checks to access metadata of posts they should not have permission to view. Versions 2026.3.0-la…
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Medium 4.4
Discourse has stored click‑based XSS via Graphviz SVG javascript: links
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the discourse-graphviz plugin contains a stored cross-site scripting (XSS) vulnerability that allows authenticated users to inject malicious JavaScri…
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Medium 4.3
Discourse fixes loose hostname matching in spam host allowlist
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the `allowed_spam_host_domains` check used `String#end_with?` without domain boundary validation, allowing domains like `attacker-example.com` to byp…
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Medium 6.5
Discourse filters whisper posts from private-posts feed
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 h…
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Medium 5.4
Discourse hardens chat DM channel creation and expansion
Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have two authorization issues in the chat direct message API. First, when creating a direct message channel or adding users to an existing one, the `t…
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Medium 4.3
Discourse prevents hidden profile data leak via user onebox
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, when a user has `hide_profile` enabled, their bio, location, and website were still exposed through the user onebox preview. An authenticated user co…
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Medium 6.9
Discourse discloses restricted post-action counts to non-privileged users
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.…
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Medium 6.9
Discourse leaks private topic metadata to non-authorized users
Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a vulnerability in an API endpoint that discloses private topic metadata of admin users to moderator users even if the moderators do not have acc…
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Medium 5.1
Discourse has Stored XSS in AI Triage Automation
Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a cross-site scripting vulnerability that arises because the system trusts the raw output from an AI Large Language Model (LLM) and renders it us…
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Medium 5.1
Discourse Vulnerable to Stored XSS via Shared AI Conversation Onebox
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the onebox method in the SharedAiConversation model renders the conversation title directly into HTML without proper sanitization. Versions 2026.3.0-…
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Medium 6.9
Discourse has a bypass of official warnings messages by non-staff users
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a type coercion issue in a post actions API endpoint allowed non-staff users to issue warnings to other users. Warnings are a staff-only moderation f…
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Medium 5.3CVE-2026-27454 Scanner template
Discourse has check revision visibility on posts endpoint
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 …
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Medium 4.1
Discourse vulnerable to HTML injection via prohibited iframe URLs
Discourse is an open source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2, insufficient cleanup in the default Codepen allowed iframes value allows an attacker to trick a user into changing the URL of the main page. This issu…
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Medium 5.3
Discourse's Fail-Open Access Control in Data Explorer Plugin Allows Unauthorized SQL Query Execution
Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, fail-open access control in Data Explorer plugin allows any authenticated user to execute SQL queries that have no explicit group assignments, including buil…