Vulnerability · Published Aug 17, 2026 · Assigned by GitHub_M
CVE-2026-63670ApostropheCMS: Mutation-XSS / allowedTags bypass via literal `</textarea/>` solidus close
Medium 6.1
In plain English
A medium-severity cross-site scripting in apostrophe from apostrophecms. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | sanitize-html | 2.17.6 | GHSA-jxwj-j7wr-gfrw |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| apostrophecms | apostrophe | < 2.17.6 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N