Server-Side Request Forgery (SSRF) in Craft CMS - CVE-2026-55791
Published: June 16, 2026
Vulnerability identifier: #VU134675
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55791
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform server-side request forgery.
The vulnerability exists due to improper access control in the /actions/app/resource-js endpoint when handling requests with a poisoned Host or X-Forwarded-Host header. A remote attacker can send a specially crafted request to perform server-side request forgery.
The issue manifests when assetManager.cacheSourcePaths is set to false.
Affected software
Craft CMS
How to mitigate CVE-2026-55791
Install security update from vendor's website.
Craft CMS - addressed in versions 4.18.0, 5.10.0