CVE-2026-83617

High

Description

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.

SeverityHigh
CVSS8.7
Exploit probability—
Product@xmldom/xmldom
PublishedSep 1, 2026
First seenSep 1, 2026

How to fix

Update
  • @xmldom/xmldom0.9.12 or later

Affected products

ProductAffected versionsFixed in
@xmldom/xmldomnpm0.9.11 ≤ v < 0.9.120.9.12

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