CVE-2026-83612: @xmldom Xmldom

High severity, CVSS 8.7. EPSS: 0.5% 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. From 0.9.0-beta.1 until 0.9.12, HTML-mode parsing through DOMParser.parseFromString() mishandles a mixed-case closing tag for the script, style, textarea, or title raw-text elements. parseHtmlSpecialContent, selected by isHTMLRawTextElement or isHTMLEscapableRawTextElement, uses a case-sensitive indexOf() and then calls substring() with a missing-close result of negative one, causing unstable parser progression and quadratic output amplification. A small untrusted text/html document can consequently consume disproportionate CPU and memory when parsed and serialized. This issue is fixed in @xmldom/xmldom version 0.9.12.

Affected products

• @xmldom Xmldom: from 0.9.0-beta.1, before 0.9.12 (fixed in 0.9.12)
• Xmldom Xmldom: from 0.9.0-beta.1, before 0.9.12 (fixed in 0.9.12)

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