Quick answers
- Is CVE-2026-50283 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-50283 being exploited in the wild.
- How severe is CVE-2026-50283?
- Medium severity, with a CVSS score of 4, published 1 July 2026.
- Which products and versions are affected?
- craftcms/cms (Packagist) ECOSYSTEM:introduced=5.0.0-RC1,fixed=5.9.21.
- Is there a fix for CVE-2026-50283?
- Yes. craftcms/cms (Packagist): upgrade to 5.9.21 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-50283 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-50283?
- Check whether you run craftcms/cms (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- craftcms/cms (Packagist): upgrade to 5.9.21 or later
composer require craftcms/cms:^5.9.21
Technical details
An authorization bypass exists in Craft CMS's `AssetsController::actionReplaceFile()` due to improper permission validation when both an `assetId` and `sourceAssetId` are provided. The controller uses a ternary expression `($assetToReplace ?: $sourceAsset)` to check permissions; when both IDs are present, it only validates the 'replace' permission for the target asset and fails to verify 'delete' permissions for the source asset. Consequently, the application copies the source file to the target and then invokes `deleteElement()` on the source asset. An authenticated attacker with file replacement privileges in any volume can exploit this to delete assets in other volumes, provided they know the target asset's ID. This issue is patched in versions 4.17.14 and 5.9.21.
Affected products
- Pixel & Tonic Craft CMS >= 4.0.0-RC1, < 4.17.14; >= 5.0.0-RC1, < 5.9.21
Identifiers
- CVE-2026-50283
- GHSA-qh45-9g5p-m2v4
Timeline
- 2026-05-29: disclosed: Initial disclosure to vendor
- 2026-07-01: advisory: NVD publication date
- 2026-07-02: patched: GitHub Advisory published and versions patched
References
- https://api.github.com/users/davidbors-snyk
- https://github.com/davidbors-snyk
- https://api.github.com/users/davidbors-snyk/gists%7B/gist_id%7D
- https://api.github.com/users/davidbors-snyk/repos
- https://avatars.githubusercontent.com/u/240482518?v=4
- https://api.github.com/users/davidbors-snyk/events%7B/privacy%7D