CVE-2026-56384: Craft CMS CMS

Medium severity, CVSS 4.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Craft CMS contains a missing authorization vulnerability in the assets/preview-thumb endpoint. A Control Panel user without permission to view a target private asset can call the endpoint with an attacker-controlled assetId and receive preview HTML containing a signed fallback transform preview link for that private asset, because no asset-view permission check is performed before preview generation. This affects versions >= 4.0.0-RC1, <= 4.17.7 and >= 5.0.0-RC1, <= 5.9.13, and is fixed in 4.17.8 and 5.9.14.

Affected products

• Craft CMS CMS: from 4.0.0-RC1, before 4.17.8 (fixed in 4.17.8); from 5.0.0-RC1, before 5.9.14 (fixed in 5.9.14)

Published 2026-06-21. Last modified 2026-06-24.