CVE-2026-28696: Craftcms/cms Craft CMS Has IDOR Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7x43-mpfg-r9wj",
  "modified" : "2026-03-04T18:38:55Z",
  "published" : "2026-03-03T20:38:55Z",
  "aliases" : [ "CVE-2026-28696" ],
  "summary" : "Craft CMS has IDOR via GraphQL @parseRefs",
  "details" : "The GraphQL directive `@parseRefs`, intended to parse internal reference tags (e.g., `{user:1:email}`), can be abused by both authenticated users and unauthenticated guests (if a Public Schema is enabled) to access sensitive attributes of any element in the CMS. The implementation in `Elements::parseRefs` fails to perform authorization checks, allowing attackers to read data they are not authorized to view.\n\n## Vulnerability Details\n\n`craft\\services\\Elements::parseRefs` identifies reference tags and resolves them using `_getRefTokenReplacement`. This method fetches the referenced element and accesses the specified attribute via $element->$attribute.\n\n- Missing Auth Check: It bypasses `canView()` checks.\n- Polymorphic Access: `getElementTypeByRefHandle` allows referencing any element type (entry, asset, user, category).\n- Custom Field Access: Since Craft elements use `__get()` to resolve custom field handles, an attacker is not limited to core attributes. They can exfiltrate any custom field data by enumerating the field handle (e.g. `{entry:123:privateNotes}`).\n\n## Attack Vectors\n\n1. Privilege Escalation / User Data Leak\n\nAn attacker can enumerate sensitive attributes of administrators or other users.\n\n- Payload: `{user:1:email}` or `{user:1:photoId}`\n\n2. Arbitrary Property Reflection & Server-Side Logic Execution\n\nThe vulnerability allows reflecting any accessible property of the underlying Element model.\n\n- Username/Admin Enumeration: `{user:1:username}` (Confirmed: returns admin), {user:1:admin}.\n- Internal Path Disclosure: Accessing methods that trigger errors (e.g., `{user:1:authKey}`) exposes full server stack traces in the GraphQL error response (e.g., Exception: No user session token exists with paths like `/var/www/html/...`).\n\n3. IDOR on Private Entries & Assets (Polymorphism)\n\nThe vulnerability is not limited to Users. Reference tags can target any element type.\n\n- Payload: `{entry:456:myConfidentialField}` (Bypasses canView checks).\n- Asset Path Leakage: `{volume:1:path}` can expose internal file system paths.\n\n4. Unauthenticated Exploitation (Public Schema)\n\nConfirmed locally. The `@parseRefs` directive is active in the Public Schema. By injecting a payload into a public-facing field (e.g., a \"News\" entry title), an unauthenticated guest can trigger the resolution and retrieve the sensitive output.\n\n## Steps to Reproduce\n\n1. Setup (Admin Panel):\n- Create a Section (e.g., \"News\") and an Entry Type.\n- Create a new Entry in that section. Set the Title to the payload: {user:1:username} or {user:1:email}.\n- Go to GraphQL > Schemas > Public Schema. Enable it, and ensure \"Query for elements in the Site\" and \"News\" section queries are checked.\n\n2. Execute Exploit (Unauthenticated):\n- Send a POST request to http://localhost:8000/index.php?action=graphql/api:\n```\ncurl -X POST \\\n-H \"Content-Type: application/json\" \\\n-d '{\"query\": \"{ entries { title @parseRefs } }\"}'\n```\n\n3. Observation:\n- The API returns `{\"data\":{\"entries\":[{\"title\":\"admin\"}]}}` (or the email).\n- Using `{user:1:authKey}` triggers an internal server error that leaks the full server path in string format.\n\n## Impact\n\n- Critical Information Disclosure: Full PII enumeration (emails, usernames).\n- System Information Leakage: Absolute server paths via stack traces.\n- Authentication Bypass: Guest accounts can effectively query the database as the system user.\n\n## Recommended Fix\n\nModify `Elements::parseRefs` to enforce `canView` permissions on the resolved element before extracting attributes.\n\n## References\n\nhttps://github.com/craftcms/cms/commit/4d98a07e47580f1712095825d3e3c4d67bc9f8b9",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0-RC1"
      }, {
        "fixed" : "4.17.0-beta.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0-RC1"
      }, {
        "fixed" : "5.9.0-beta.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/security/advisories/GHSA-7x43-mpfg-r9wj"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-28696"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/commit/4d98a07e47580f1712095825d3e3c4d67bc9f8b9"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/craftcms/cms"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-03T20:38:55Z",
    "nvd_published_at" : "2026-03-04T17:16:21Z"
  }
}