High 8.7Published Sep 1, 2026

CVE-2026-83618xmldom: requireWellFormed DocType publicId/systemId validation is bypassable via an embedded line terminator

Updated under an hour ago (2026-10-19 09:10 UTC)

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Exploited in the last 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.

CVSS: 8.7 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness (CWE): CWE-91, CWE-625
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Sep 4, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

xmldom xmldom xmldom:xmldom (from the name)	from 0.9.10, < 0.9.12	CNA record

References

https://github.com/xmldom/xmldom/security/advisories/GHSA-vr34-hp96-76ppx-refsource-confirm
https://github.com/xmldom/xmldom/pull/1071x-refsource-misc
https://github.com/xmldom/xmldom/commit/7b2ec67e1750daadd0bb06c92e875e726544a362x-refsource-misc
https://github.com/xmldom/xmldom/releases/tag/0.9.12x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.