to break out of the intended HTML context and execute arbitrary JavaScript in the browser of any authenticated user who views the affected page. This can be leveraged to perform authenticated API requests, access sensitive data such as usernames, email addresses, and roles via internal APIs, and exfiltrate it to an attacker-controlled server. This issue has been fixed in version 4.29.0.", "datePublished": "2026-04-15T19:34:23Z", "dateModified": "2026-05-14T16:07:20Z", "keywords": "CVE-2026-35569, vulnerability, CVE, security, apostrophe, apostrophecms", "about": { "@type": "SoftwareApplication", "name": "apostrophe", "applicationCategory": "SecurityApplication", "operatingSystem": "All" } }
CVE-2026-35569 HIGH

CVE-2026-35569: ApostropheCMS: Stored XSS in SEO Fields Leads to Authenticated API Data Exposure in ApostropheCMS

Vendor Apostrophecms
Product apostrophe
Weakness CWE-79 · XSS
Published April 15, 2026
Last update May 14, 2026

CVSS base score

8.7/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

What the vulnerability does

01Description

ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain a stored cross-site scripting vulnerability in SEO-related fields (SEO Title and Meta Description), where user-controlled input is rendered without proper output encoding into HTML contexts including <title> tags, <meta> attributes, and JSON-LD structured data. An attacker can inject a payload such as "></title><script>alert(1)</script> to break out of the intended HTML context and execute arbitrary JavaScript in the browser of any authenticated user who views the affected page. This can be leveraged to perform authenticated API requests, access sensitive data such as usernames, email addresses, and roles via internal APIs, and exfiltrate it to an attacker-controlled server. This issue has been fixed in version 4.29.0.

Key dates

02Disclosure timeline

April 15, 2026 CVE published
May 14, 2026 Record updated

Related vulnerabilities

04Related CVE