What’s Vulnerable › Vulnerabilities

CVE-2026-83617: xmldom: requireWellFormed element/attribute name validation is bypassable via an embedded line terminator

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-01 · updated 2026-09-08
• Weakness: CWE-91

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.

Affected products

• xmldom: from 0.9.11, < 0.9.12

References

• https://github.com/xmldom/xmldom/commit/7b2ec67e1750daadd0bb06c92e875e726544a362
• https://github.com/xmldom/xmldom/pull/1071
• https://github.com/xmldom/xmldom/releases/tag/0.9.12
• https://github.com/xmldom/xmldom/security/advisories/GHSA-jxjr-3g7g-3944
• https://github.com/xmldom/xmldom/security/advisories/GHSA-jxjr-3g7g-3944

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