---
id: CVE-2026-56384
title: Craft CMS - Missing Authorization in assets/preview-thumb Endpoint
summary: >-
  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 p…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-862
vendor: craftcms
product: cms
affected:
  - cms >= 4.0.0-RC1 < 4.17.8
  - cms >= 5.0.0-RC1 < 5.9.14
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-24T15:40:42.349785Z'
published: '2026-06-21'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:06:09.897Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-56384'
references:
  - url: 'https://github.com/craftcms/cms/security/advisories/GHSA-x76w-8c62-48mg'
    label: GitHub Security Advisory (GHSA-x76w-8c62-48mg)
  - url: >-
      https://github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27
    label: >-
      https://github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27
  - url: >-
      https://www.vulncheck.com/advisories/craft-cms-missing-authorization-in-assets-preview-thumb-endpoint
    label: >-
      VulnCheck Advisory: Craft CMS - Missing Authorization in
      assets/preview-thumb Endpoint
tags:
  - cve.org
epss: 0.00331
epssPercentile: 0.26445
ingestedAt: '2026-11-08T14:51:22.349Z'
---

## Overview

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

- `cms >= 4.0.0-RC1 < 4.17.8`
- `cms >= 5.0.0-RC1 < 5.9.14`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.