CVE-2026-83618: @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 0.9.10 until 0.9.12, the requireWellFormed: true serializer validates DocumentType.publicId and DocumentType.systemId with PubidLiteral_match and SystemLiteral_match expressions produced by reg() in lib/grammar.js, which inherit the multiline flag. A complete valid literal on the first line can therefore satisfy the matcher while U+000A, U+000D, U+2028, or U+2029 and breakout markup remain in the emitted <!DOCTYPE ...> declaration. This bypasses the strict-serialization mitigation for the earlier DocumentType injection advisory; creation and direct property assignment remain unvalidated by design. This issue is fixed in @xmldom/xmldom version 0.9.12.

Affected products

• @xmldom Xmldom: from 0.9.10, before 0.9.12 (fixed in 0.9.12)
• Xmldom Xmldom: from 0.9.10, before 0.9.12 (fixed in 0.9.12)

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