CVE-2026-55424: Discourse

Medium severity, CVSS 5.4. EPSS: 0.4% chance of exploitation in the next 30 days.

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, a topic "featured link" was not sufficiently normalized and escaped before being rendered in the topic list, allowing a user who can set a featured link to inject JavaScript when default Content Security Policy protections were modified or disabled. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

Affected products

• Discourse Discourse: from 2026.1.0, before 2026.1.5 (fixed in 2026.1.5); from 2026.4.0, before 2026.4.2 (fixed in 2026.4.2); from 2026.5.0, before 2026.5.1 (fixed in 2026.5.1); version 2026.6.0 only

Published 2026-07-09. Last modified 2026-07-14.