# CVE-2026-83607: xmldom: Element name injection via createElement() bypasses requireWellFormed

CVE-2026-83607 is fixed in node-xmldom on 1 platform by DEBIAN-CVE-2026-83607 (version 0.9.11-1), released September 2, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-83607
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0061
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 1, 2026
- Weakness: XML Injection (aka Blind XPath Injection)
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83607

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | node-xmldom Debian 14 | 0.9.11-1 | [DEBIAN-CVE-2026-83607](https://patchblox.com/security/data/fix/linux/debian-cve-2026-83607.md) | Sep 2, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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