CVE-2026-83615: @xmldom Xmldom

High severity, CVSS 8.7. EPSS: 0.6% chance of exploitation in the next 30 days.

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom versions 0.1.5 through 0.6.0, appendElement in lib/sax.js uses _copy to clone the complete currentNSMap for each nested element that declares a new namespace prefix. Keeping every ancestor map live on the parse stack creates quadratic peak namespace-map storage, so a small highly compressible XML document can exhaust the process heap before application validation. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

Affected products

• @xmldom Xmldom: from 0.7.0, before 0.8.15 (fixed in 0.8.15); from 0.9.0, before 0.9.12 (fixed in 0.9.12)
• Xmldom Xmldom: from 0.1.5, up to and including 0.6.0

Published 2026-09-01. Last modified 2026-09-08.