CVE-2026-56384

Medium

Description

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.

SeverityMedium

CVSS4.3

Exploit probability—

ProductCraftcms/cms

PublishedJun 21, 2026

First seenJun 21, 2026

Weakness typeCWE-862Missing authorization

How to fix

Update

craftcms/cms4.17.8, 5.9.14 or later

Patches

github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27

Vendor advisories

github.com/craftcms/cms/security/advisories/GHSA-x76w-8c62-48mg

Affected products

Product	Affected versions	Fixed in
craftcms/cmsPackagist	4.0.0-RC1 ≤ v < 4.17.8, 5.0.0-RC1 ≤ v < 5.9.14	4.17.8, 5.9.14

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