Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, a hostname validation issue in FinalDestination could allow bypassing SSRF protections under certain conditions. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. No known workarounds are available.
Weakness
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Discourse | Discourse | * | 3.5.4 (excluding) |
| Discourse | Discourse | 2025.11.0 (including) | 2025.11.2 (excluding) |
| Discourse | Discourse | 2025.12.0 (including) | 2025.12.0 (including) |
| Discourse | Discourse | 2026.1.0 (including) | 2026.1.0 (including) |