CVE-2026-59828: Discourse

Medium severity, CVSS 5.3. EPSS: 0.5% 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, post revisions that should be hidden from regular users could be leaked through visible diffs on adjacent revisions serialized by PostRevisionSerializer. 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 2026-07-13.