Craft CMS is a content management system (CMS). Versions 4.0.0-RC1 and above, prior to 4.18.0 and 5.0.0-RC1, and above, prior to 5.10.0, are vulnerable to Server-Side Request Forgery (SSRF) and Arbitrary JavaScript Injection through the /actions/app/resource-js endpoint. By exploiting the default permissive trustedHosts configuration, an attacker can poison the Host or X-Forwarded-Host header to manipulate the application’s $baseUrl. This bypasses the endpoint’s internal URL validation, forcing the backend Guzzle client to fetch a malicious payload from an attacker-controlled server and reflect it to the client with a Content-Type: application/javascript header. The vulnerability manifests when assetManager.cacheSourcePaths is set to false. This issue has been fixed in versions 4.18.0 and 5.10.0.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
craftcms cms affected
Version Status Constraints
>= 5.0.0-RC1, < 5.10.0 affected —
>= 4.0.0-RC1, < 4.18.0 affected —

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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-c55v-343g-5xff Craft CMS: Blind SSRF and Arbitrary JavaScript Injection via Host Header Poisoning in actionResourceJs
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/craftcms/cms/pull/18559 cve-icon
https://github.com/craftcms/cms/security/advisories/GHSA-c55v-343g-5xff cve-icon
History

Wed, 01 Jul 2026 23:45:00 +0000

Type Values Removed Values Added
Description Craft CMS is a content management system (CMS). Versions 4.0.0-RC1 and above, prior to 4.18.0 and 5.0.0-RC1, and above, prior to 5.10.0, are vulnerable to Server-Side Request Forgery (SSRF) and Arbitrary JavaScript Injection through the /actions/app/resource-js endpoint. By exploiting the default permissive trustedHosts configuration, an attacker can poison the Host or X-Forwarded-Host header to manipulate the application’s $baseUrl. This bypasses the endpoint’s internal URL validation, forcing the backend Guzzle client to fetch a malicious payload from an attacker-controlled server and reflect it to the client with a Content-Type: application/javascript header. The vulnerability manifests when assetManager.cacheSourcePaths is set to false. This issue has been fixed in versions 4.18.0 and 5.10.0.
Title Craft CMS: Blind SSRF and Arbitrary JavaScript Injection via Host Header Poisoning in actionResourceJs
Weaknesses CWE-644
CWE-79
CWE-918
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-01T23:13:58.321Z

Reserved: 2026-06-17T14:40:28.380Z

Link: CVE-2026-55791

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-07-02T07:15:16Z

Weaknesses