CVE-2026-83617: @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. From 0.9.11 until 0.9.12, the requireWellFormed: true element and attribute name checks use the anchored QName_exact expression produced by reg() in lib/grammar.js, which inherits the multiline flag. A name with a valid first line followed by U+000A, U+000D, U+2028, or U+2029 and breakout markup therefore passes validation and is emitted verbatim in element start and end tags or attribute names. This bypasses the strict-serialization checks introduced for the earlier element-name and attribute-name injection advisories, while the default serialization path remains outside the strict guarantee. This issue is fixed in @xmldom/xmldom version 0.9.12.

Affected products

• @xmldom Xmldom: from 0.9.11, before 0.9.12 (fixed in 0.9.12)
• Xmldom Xmldom: from 0.9.11, before 0.9.12 (fixed in 0.9.12)

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