Craft CMS: Authorized asset "preview file" requests bypass allows users without asset access to retrieve private preview metadata

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

1.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U · score source

EPSS

• CVE-2026-56385: 0.36% estimated exploitation activity in the next 30 days; percentile 29.75 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary An authenticated low-privileged user can call assets/preview-file for an asset they are not authorized to view and still receive preview response data (previewHtml) for that private asset. The returned preview HTML included a private preview image route containing the target private assetId, even though canView was false for the attacker account. Details 1. assets/preview-file accepts a maliciously controlled assetId and renders preview output. 2. The action does not enforce per-asset view authorization prior to returning preview content. 3. As a result, an authenticated user without asset-view permission can still obtain private preview output. This affects Craft installations with authenticated users of mixed privilege levels with private assets. Resources - d30df3112220db1ffd6726a3ed11857014c7fb27 - b1cddf72c98a

Published by the source

26 Mar 2026, 17:12 UTC

Last modified by the source

6 Aug 2026, 21:56 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-44px-qjjc-xrhq

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# Patch Next advisory brief: CVE-2026-56385

Advisory: Craft CMS: Authorized asset "preview file" requests bypass allows users without asset access to retrieve private preview metadata
IDs: CVE-2026-56385, GHSA-44px-qjjc-xrhq
Record: https://patchnext.com/advisories/cve-2026-56385 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 1.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: craftcms/cms 5.9.14, 4.17.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist craftcms/cms: affected >= 5.0.0-RC1, <= 5.9.13; >= 4.0.0-RC1, <= 4.17.7; fixed in 5.9.14, 4.17.8

## Suggested inspection (read-only)
- Packagist craftcms/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on craftcms/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-44px-qjjc-xrhq (GitHub-reviewed advisory GHSA-44px-qjjc-xrhq lists affected ranges: Packagist craftcms/cms >=5.0.0-RC1 =4.0.0-RC1 <=4.17.7)

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