CVE-2026-63670

ApostropheCMS: Mutation-XSS / allowedTags bypass via literal `</textarea/>` solidus close

Published: Aug 17, 2026Updated: Sep 9, 2026 Sources: CVE List NVDCWE-79

6.1MEDIUM

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:RUser Interaction

Required

Scope

S:CScope

Changed

Impact

C:LConfidentiality

Low

I:LIntegrity

Low

A:NAvailability

None

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Weaknesses

CWE-79

Affected Products

apostrophecms

commercialaka apostrophe

apostropheOn-prem

Web & CMS Plugins / cms-core

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Execution

Initial Access

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References

https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-jxwj-j7wr-gfrw

github.com

https://github.com/apostrophecms/apostrophe/pull/5501

github.com

https://github.com/apostrophecms/apostrophe/commit/eae1fb2b72ec5d1c27d0977509c6482a0408f725

github.com

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