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Vulnerability · Published Sep 1, 2026 · Assigned by GitHub_M

CVE-2026-84371ApostropheCMS: Stored XSS via SVG SMIL URI-list scheme-policy bypass

Medium 5.4

In plain English

A medium-severity cross-site scripting in apostrophe from apostrophecms. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.3%top 77.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
npmsanitize-html2.17.7GHSA-g8qq-57p8-ggw5

Affected products (as reported)

VendorProductVersions
apostrophecms apostrophe >= 1.9.0, < 2.17.7

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References