CVE-2026-41130: Craftcms/cms Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-95wr-3f2v-v2wh",
  "modified" : "2026-04-24T20:42:23Z",
  "published" : "2026-04-14T23:36:09Z",
  "aliases" : [ "CVE-2026-41130" ],
  "summary" : "Craft CMS has a host header injection leading to SSRF via resource-js endpoint",
  "details" : "### Summary\n\nThe `resource-js` endpoint in Craft CMS allows unauthenticated requests to proxy remote JavaScript resources. \nWhen `trustedHosts` is not explicitly restricted (default configuration), the application trusts the client-supplied Host header. \n\nThis allows an attacker to control the derived `baseUrl`, which is used in prefix validation inside `actionResourceJs()`. \nBy supplying a malicious Host header, the attacker can make the server issue arbitrary HTTP requests, leading to Server-Side Request Forgery (SSRF).\n\n### Details\n\nThe vulnerability exists in `AppController::actionResourceJs()`.\n\nThe function validates that the `url` parameter starts with `assetManager->baseUrl`. However, `baseUrl` is derived from the current request host. If `trustedHosts` is not configured, the Host header is fully attacker-controlled.\n\nAttack chain:\n\n1. Attacker sends request with controlled `Host` header.\n2. Application derives `baseUrl` from the malicious Host.\n3. `url` parameter is required to start with this `baseUrl`.\n4. Validation passes.\n5. Guzzle performs a server-side HTTP request to the attacker-controlled host.\n6. SSRF occurs.\n\nThis does not rely on string parsing bypass. It relies on Host header trust.\n\n### PoC (safe reproduction steps)\n\nEnvironment:\n- Craft CMS 5.9.12\n- Default configuration (no trustedHosts restriction)\n- Docker deployment\n\n1. Start a listener inside the container:\n   python3 -m http.server 9999\n\n2. Send a request to resource-js with a controlled Host header.\n\n3. Observe that the internal listener receives a request (OOB confirmation).",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0-RC1"
      }, {
        "fixed" : "5.9.15"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.9.14"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0-RC1"
      }, {
        "fixed" : "4.17.9"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.17.8"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/security/advisories/GHSA-95wr-3f2v-v2wh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-41130"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/commit/ebe7e85f1c89700d64332f72492be2e9a594e783"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/craftcms/cms"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-14T23:36:09Z",
    "nvd_published_at" : "2026-04-22T00:16:28Z"
  }
}