CVE-2026-59830: Discourse

Medium severity, CVSS 5.4. EPSS: 0.3% chance of exploitation in the next 30 days.

Discourse is an open-source discussion platform. Prior to 2026.7.0, the post action component failed to escape user-controlled display names before interpolating them into an HTML string passed to trustHTML. A user who could choose a crafted display name could persist markup in post action descriptions. Viewing the affected user activity streams could execute attacker-controlled script in another user's browser. This issue is fixed in version 2026.7.0.

Affected products

• Discourse Discourse: before 2026.7.0 (fixed in 2026.7.0)

Published 2026-09-21. Last modified 2026-09-23.