# CVE-2026-83607

## Summary

- **CVE ID:** CVE-2026-83607
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-91
- **Published:** Sep 1, 2026
- **Last Modified:** Sep 1, 2026

## Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.14 and 0.9.11, and in xmldom version 0.6.0 and earlier, Document.createElement(tagName) stores an unvalidated element name and XMLSerializer.serializeToString() emits that name verbatim. The requireWellFormed: true path did not validate the element qualified name or synthesized xmlns:PREFIX declaration, so attacker-controlled tag names could inject attributes, elements, or processing instructions into serialized XML or HTML and could cause cross-site scripting when browser-consumed. The unchecked values violate the XML QName constraint, and default serialization and creation-time createElement() behavior remain permissive. This issue is fixed in @xmldom/xmldom versions 0.8.14 and 0.9.11; no fixed version is available for xmldom.

## Affected Products

- xmldom — xmldom (<= 0.6.0)
- @xmldom — xmldom (>= 0.7.0, < 0.8.14)
- @xmldom — xmldom (>= 0.9.0, < 0.9.11)

## References

- [CNA](https://github.com/xmldom/xmldom/security/advisories/GHSA-w2rr-34g9-rvrj)
- [CNA](https://github.com/xmldom/xmldom/pull/1043)
- [CNA](https://github.com/xmldom/xmldom/pull/1050)
- [CNA](https://github.com/xmldom/xmldom/commit/cba1321218b069182695813fa7565653708e172e)
- [CNA](https://github.com/xmldom/xmldom/commit/d8212e632507eaf1d9f609657dd4c56abeb12d44)
- [CNA](https://github.com/xmldom/xmldom/releases/tag/0.8.14)
- [CNA](https://github.com/xmldom/xmldom/releases/tag/0.9.11)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.35%
- **EPSS Percentile:** 27.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._