Summary
Craft CMS: Authenticated "assets/preview-thumb" discloses signed fallback transform preview link to CP users without asset-view permission
A user with Control Panel access but without permission to view a target private asset can call assets/preview-thumb and receive preview HTML that contains a signed fallback transform link for that private asset.
Details
Root-cause analysis:
- The endpoint accepts an attacker-controlled
assetId. - Asset is resolved, and thumbnail HTML is returned.
- No explicit asset-view permission check is performed before preview generation.
Resources
https://github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27
Impact
Type:
- Missing authorization
- Unauthorized preview-link disclosure
Affected deployments:
- Craft sites with control panel users who have partial permissions and private assets.
Security consequence:
- A control panel user without asset-view permission can still obtain signed preview transform link data for private assets.
- This may increase private asset exposure risk depending on deployment and endpoint chaining.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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craftcms/cms to 4.17.8 or later; craftcms/cms to 5.9.14 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-X76W-8C62-48MG? GHSA-X76W-8C62-48MG is a medium-severity missing authorization vulnerability in craftcms/cms (composer), affecting versions >= 4.0.0-RC1, <= 4.17.7. It is fixed in 4.17.8, 5.9.14. The application does not perform an authorization check before performing a sensitive operation.
- Which versions of craftcms/cms are affected by GHSA-X76W-8C62-48MG? craftcms/cms (composer) versions >= 4.0.0-RC1, <= 4.17.7 is affected.
- Is there a fix for GHSA-X76W-8C62-48MG? Yes. GHSA-X76W-8C62-48MG is fixed in 4.17.8, 5.9.14. Upgrade to this version or later.
- Is GHSA-X76W-8C62-48MG exploitable, and should I be worried? Whether GHSA-X76W-8C62-48MG is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-X76W-8C62-48MG is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-X76W-8C62-48MG?
- Upgrade
craftcms/cmsto 4.17.8 or later - Upgrade
craftcms/cmsto 5.9.14 or later
- Upgrade