CVE-2026-83609

What it is

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0 until 0.9.12, the shared reg() builder in lib/grammar.js compiles the anchored QName_exact validator with the multiline flag, so ^ and $ validate only one line instead of the complete name. createElementNS, createAttributeNS, createDocumentType, and createAttribute consequently accept a malformed XML name whose first line is valid and whose later text injects markup when serialized through either the default path or requireWellFormed: true. The triggering ECMAScript line terminators are U+000A, U+000D, U+2028, and U+2029. This issue is fixed in @xmldom/xmldom version 0.9.12.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-01 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-08 21:11 UTC Last updatedMost recent change to the record

Details

Published

2026-09-01 15:17 UTC

Last modified

2026-09-08 21:11 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-91

Record status

Deferred

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

High

Availability

None