CVE-2026-56384: Missing Authorization in craftcms cms
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.
AI Analysis
Technical Summary
CVE-2026-56384 is a missing authorization vulnerability in Craft CMS affecting the assets/preview-thumb endpoint. A Control Panel user lacking permission to view a private asset can exploit this by supplying an attacker-controlled assetId, resulting in preview HTML that includes a signed fallback transform preview link for that private asset. This occurs because the system does not perform an asset-view permission check before generating the preview. The issue affects versions >=4.0.0-RC1 and <=4.17.7, as well as >=5.0.0-RC1 and <=5.9.13, and is resolved in versions 4.17.8 and 5.9.14.
Potential Impact
Unauthorized users with Control Panel access but without asset-view permissions can gain access to preview information of private assets, potentially exposing sensitive content previews. The vulnerability does not require user interaction and can be exploited remotely with low attack complexity. The overall impact is rated medium.
Mitigation Recommendations
A fix is available in Craft CMS versions 4.17.8 and 5.9.14. Users should upgrade to these or later versions to remediate this vulnerability. No vendor advisory content was provided to indicate alternative mitigations or temporary fixes.
CVE-2026-56384: Missing Authorization in craftcms cms
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.
CVSS v4.0
Score 5.3medium
Affected software
pkg:github/craftcms/cmsRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-56384 is a missing authorization vulnerability in Craft CMS affecting the assets/preview-thumb endpoint. A Control Panel user lacking permission to view a private asset can exploit this by supplying an attacker-controlled assetId, resulting in preview HTML that includes a signed fallback transform preview link for that private asset. This occurs because the system does not perform an asset-view permission check before generating the preview. The issue affects versions >=4.0.0-RC1 and <=4.17.7, as well as >=5.0.0-RC1 and <=5.9.13, and is resolved in versions 4.17.8 and 5.9.14.
Potential Impact
Unauthorized users with Control Panel access but without asset-view permissions can gain access to preview information of private assets, potentially exposing sensitive content previews. The vulnerability does not require user interaction and can be exploited remotely with low attack complexity. The overall impact is rated medium.
Mitigation Recommendations
A fix is available in Craft CMS versions 4.17.8 and 5.9.14. Users should upgrade to these or later versions to remediate this vulnerability. No vendor advisory content was provided to indicate alternative mitigations or temporary fixes.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-06-21T02:05:47.495Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a37ed4baaf2dc2701b22764
Added to database: 06/21/2026, 13:55:23 UTC
Last enriched: 06/21/2026, 14:10:07 UTC
Last updated: 06/21/2026, 14:57:02 UTC
Views: 7
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