Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
https://github.com/discourse/discourse/security/advisories/GHSA-7wq5-jgww-5rw3
https://github.com/discourse/discourse/releases/tag/v2026.6.0
https://github.com/discourse/discourse/releases/tag/v2026.5.1
https://github.com/discourse/discourse/releases/tag/v2026.4.2
https://github.com/discourse/discourse/releases/tag/v2026.1.5
https://github.com/discourse/discourse/commit/ca5a7e06167561928556afa2f237d67e459c6914