Discourse is an open source discussion platform. Prior to versions 3.5.3, 2025.11.1, and 2025.12.0, an attacker who knows part of a username can find the user and their full name via UI or API, even when `enable_names` is disabled. Versions 3.5.3, 2025.11.1, and 2025.12.0 contain a fix.
https://github.com/discourse/discourse/security/advisories/GHSA-c59w-jwx7-34v4
https://github.com/discourse/discourse/commit/e936a523b5900a9d866d23ea3da904ba12bb0fb2
https://github.com/discourse/discourse/commit/6192f55629624925595dae14364fd86cac0f09df
https://github.com/discourse/discourse/commit/1cb45b8b287597085e3514596ffb1d9b41938f81
Published: 2025-12-30
Updated: 2026-02-20
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Severity: Medium
Base Score: 6.3
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
Severity: Medium
EPSS: 0.00041