What’s Vulnerable › Vulnerabilities
CVE-2025-68659: Discourse has DoS vulnerability in username change endpoint
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-01-28 · updated 2026-06-17
- Weakness: CWE-770
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.
Affected products
- discourse: before 3.5.4; from 2025.11.0 before 2025.11.2; 2025.12.0, 2026.1.0 — fixed in 2025.11.2, 3.5.4
How to fix
Upgrade to a fixed version: discourse 2025.11.2, 3.5.4. Check the vendor advisory for mitigations.
References
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