CVE-2025-68659
Discourse has DoS vulnerability in username change endpoint
Description
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.
How to fix CVE-2025-68659
To remediate CVE-2025-68659, upgrade the affected package to a fixed version below.
- —upgrade to 3.5.4 or later
Is CVE-2025-68659 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 3.5.4, >= 2025.11.0, < 2025.11.2, >= 2025.12.0, < 2025.12.1, >= 2026.1.0, < 2026.1.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |