CVE-2026-84371: Apostrophecms Apostrophe

Medium severity, CVSS 5.4. EPSS: 0.3% chance of exploitation in the next 30 days.

ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. From version 1.9.0 until version 2.17.7, packages/sanitize-html/index.js validates an animation value attribute as one flat URL and does not recognize that attributeName selecting href or xlink:href gives the sibling values, from, to, or by attribute SVG SMIL URL semantics. In configurations that allow the animate, animateColor, animateMotion, animateTransform, or set elements, a values list can begin with a safe fragment and contain a later executable destination that survives allowedSchemesAppliedToAttributes checking. When the sanitized SVG is rendered, the browser can copy that later destination into the live link, and a victim who activates the link can execute script in the application's origin. This issue is fixed in version 2.17.7.

Affected products

• Apostrophecms Apostrophe: from 1.9.0, before 2.17.7 (fixed in 2.17.7)

Published 2026-09-01. Last modified 2026-09-09.