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[ CVE-2026-112958 · Published 20 Oct 2026 ]

ApostropheCMS: Stored XSS via Unescaped Widget Style Attribute Serialization

CVSS 5.4 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

ApostropheCMS is an open-source Node.js content management system. Prior to 4.34.0, a project-defined free-form widget style field can carry an editor-controlled quote into an inline style attribute because the wrapper serializer does not apply HTML-attribute encoding. The quote can terminate the style attribute and inject executable attributes when published content, or an affected draft viewed by a higher-privileged user, is rendered. This issue is fixed in version 4.34.0.

[ Fixes ]Fixes and patches

  • apostrophe 4.34.0Fixed version · GitHub Advisories · npm package apostrophe: upgrade to 4.34.0 or later (affected < 4.34.0)

[ Packages ]Affected open-source packages

[ References ]References