CVE-2025-68659CWE-770

Discourse has DoS vulnerability in username change endpoint

Medium · published January 28, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
15.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00249 · 15.3th percentile
Weakness
CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-01-28T18:51Z
EPSS history
Timeline
  • 28 JAN 18:51Z
    Discourse has DoS vulnerability in username change endpoint
    cvelistv5