XSS in Apostrophecms Apostrophe
CVE-2026-63670
ApostropheCMS is an open-source Node.js content management system. Prior to 2.17.6, sanitizeHtml() can pass disallowed executable markup through packages/sanitize-html/index.js when textarea or xmp is included in allowedTags because a literal solidus after the raw-text end-tag name is treated as text by htmlparser2 and the ontext handler emits that content without escaping, while a browser parses the following img onerror markup as active HTML. This issue is fixed in version 2.17.6.
Vulnerability class: XSS (Cross-Site Scripting)
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Apostrophecms Apostrophe — versions < 2.17.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-63670?
- CVE-2026-63670 is a medium-severity vulnerability in Apostrophecms Apostrophe, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-08-17.
- How severe is CVE-2026-63670?
- Medium severity. CVSS v3 base score is 6.1 out of 10.