CVE-2025-68659: Discourse

Medium severity, CVSS 5.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Discourse is an open source discussion platform. Versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 have an application level denial of service vulnerabilityin the username change functionality at try.discourse.org. The vulnerability allows attackers to cause noticeable server delays and resource exhaustion by sending large JSON payloads to the username preference endpoint PUT /u//preferences/username, resulting in degraded performance for other users and endpoints. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. No known workarounds are available.

Affected products

• Discourse Discourse: before 3.5.4 (fixed in 3.5.4); from 2025.11.0, before 2025.11.2 (fixed in 2025.11.2); version 2025.12.0 only; version 2026.1.0 only

Published 2026-01-28. Last modified 2026-06-17.