Description
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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
discourse discourse
>= 2026.1.0-latest, < 2026.1.3affected>= 2026.2.0-latest, < 2026.2.2affected>= 2026.3.0-latest, < 2026.3.0affected
References
- https://github.com/discourse/discourse/security/advisories/GHSA-378j-ccw4-4fwh ↗
- https://github.com/discourse/discourse/commit/080408b93d00305b51d71f63f755f43fa601884d ↗
- https://meta.discourse.org/t/using-discourse-as-a-sso-provider/32974 ↗
- https://meta.discourse.org/t/use-discourse-as-an-identity-provider-sso-discourseconnect/32974 ↗