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.
Root-cause analysis:
assetId.Type:
Affected deployments:
Security consequence:
https://github.com/craftcms/cms/commit/d30df3112220db1ffd6726a3ed11857014c7fb27
{
"cwe_ids": [
"CWE-200",
"CWE-862"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-06T20:28:07Z",
"nvd_published_at": null,
"severity": "MODERATE"
}