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CVE-2026-33300

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 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.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
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Discourse
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Discourse
CVE-2026-33415

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 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.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-32113

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 redirects to it with allow_other_host: true without validating the destination URL. While this cookie is normally set during legitimate DiscourseConnect Provider flows with cryptographically validated SSO payloads, cookies are client-controlled and can be set by attackers. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-27934

Discourse leaks private topic title and post excerpt via user action API endpoint

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a lack of visibility checks with a user action API endpoint that results in disclosure of the title and post excerpt to unauthorized users, leading to information disclosure. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 4.0 · 8.7 High EPSS 1.2% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33423

Discourse staff can modify any user's group notification level

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, staff can modify any user's group notification level. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 4.0 · 1.3 Low EPSS < 1% KEV · Not listed
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Discourse
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Discourse
CVE-2026-33251

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.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, ensure only trusted users are part of the Site Setting for accept_all_solutions_allowed_groups.

CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33291

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 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33411

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 workaround, ensure that the Content Security Policy is enabled, and has not been modified in a way which would make it more vulnerable to XSS attacks.

CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33422

Discourse exposes ip_address of flagged user

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the `ip_address` of a flagged user is exposed to any user who can access the review queue, including users who should not be able to see IP addresses. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 3.1 · 3.5 Low EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33425

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 `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.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
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Discourse
CVE-2026-33426

Discourse users can edit or synonymize hidden tags they can't see

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, users with tag-editing permissions could edit and create synonyms for tags hidden in restricted tag groups, even if they lacked visibility into those tags. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 3.1 · 3.5 Low EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33427

Discourse Authorization Page Displays Unvalidated Redirect Domain

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an unauthenticated attacker can cause a legitimate Discourse authorization page to display an attacker-controlled domain, facilitating social engineering attacks against users. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 4.0 · 2.7 Low EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-33428

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 deleted posts index endpoint. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 4.0 · 4.9 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-30888

Discourse has moderator privilege escalation via arbitrary post_id in suspend/silence endpoint

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 allow a moderator to edit site policy documents (ToS, guidelines, privacy policy) that they are explicitly prohibited from modifying. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

CVSS 3.1 · 2.2 Low EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-30889

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-latest.1, 2026.2.1, and 2026.1.2 contain a patch.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-30891

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, 2026.2.1, and 2026.1.2 contain a patch.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-31805

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 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.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-31869

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_names referencing a hidden-membership group and probing arbitrary usernames, an attacker can infer membership based on whether user_reasons returns "private" for a given user. This bypasses group member-visibility controls. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. To work around this issue, restrict the messageable policy of any hidden-membership group to staff or group members only, so untrusted users cannot reach the vulnerable code path.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-32114

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, 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.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse
CVE-2026-27166

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 issue has been fixed in versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes.

CVSS 3.1 · 4.1 Medium EPSS < 1% KEV · Not listed
Vendors
Discourse
Products
Discourse