Origin Validation Error Affecting craftcms/cms package, versions >=4.0.0-RC1, <4.18>=5.0.0-RC1, <5.10
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-CRAFTCMSCMS-17660443
- published27 Jun 2026
- disclosed19 Jun 2026
- creditseoyoung-kang
Introduced: 19 Jun 2026
NewCVE-2026-55791 (opens in a new tab)How to fix?
Upgrade craftcms/cms to version 4.18, 5.10 or higher.
Overview
craftcms/cms is a content management system.
Affected versions of this package are vulnerable to Origin Validation Error via the actionResourceJs process. An attacker can execute arbitrary JavaScript in the context of an administrator's browser and potentially achieve remote code execution by poisoning the Host or X-Forwarded-Host headers, which manipulates the application's base URL and causes the backend to fetch and serve attacker-controlled JavaScript. This can result in web cache poisoning, leading to stored malicious scripts being executed by privileged users. This is only exploitable if assetManager.cacheSourcePaths is set to false and the default permissive trustedHosts configuration is in place.