craftcms/cms · Duplicate Advisory: Craft CMS: Authenticated "assets/preview-thumb" discloses signed fallback transform preview link to CP users without asset-view permission
Affects craftcms/cmsSource GCVE Database
CVSS 4.3 Medium · fixed in 4.17.8 : update craftcms/cms when convenient.
Data as of 7 Aug 2026, 07:00 UTC
- Patch
- Available – fixed in 4.17.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:NWhat to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Packagistcraftcms/cms | Affected
| Fixed in– |
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AI-suggested
Upgrade Craft CMS to version 4.17.8 or later in the 4.x series, or 5.9.14 or later in the 5.x series, where this vulnerability has been fixed. No other mitigations are indicated.
Description
Craft CMS versions 4.0.0-RC1 through 4.17.7 and 5.0.0-RC1 through 5.9.13 contain a missing authorization vulnerability in the assets/preview-thumb endpoint. This flaw allows Control Panel users without asset-view permission to obtain a signed fallback transform preview link for private assets by calling the endpoint with an attacker-controlled assetId. The vulnerability is fixed in versions 4.17.8 and 5.9.14.
References
- github.com/craftcms/cms/security/advisories/GHSA-x76w-8c62-48mg (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-56384 (opens in a new tab)
- github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27 (opens in a new tab)
- vulncheck.com/advisories/craft-cms-missing-authorization-in-assets-preview-thumb-endpoint (opens in a new tab)