Medium severity · published Jan 28, 2026
CVE-2025-68659
Discourse has DoS vulnerability in username change endpoint
5.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
< 3.5.4; >= 2025.11.0-latest, < 2025.11.2; >= 2025.12.0-latest, < 2025.12.1; >= 2026.1.0-latest, < 2026.1.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-68659
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-68659
Third Party Advisory
https://github.com/discourse/discourse/security/advisories/GHSA-rmp6-c9rq-6q7p
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