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, Element.setAttribute() calls the private _createAttribute(name) path without validating the attribute name, while Document.createAttribute(name) validates against QName. XMLSerializer.serializeToString() emits attribute names verbatim, and requireWellFormed: true did not validate them, so a crafted name can terminate the intended attribute and inject additional attributes, including event handlers, into browser-consumed output; synthesized xmlns:PREFIX declarations expose the same unchecked-name boundary. This issue is fixed in @xmldom/xmldom versions 0.8.14 and 0.9.11; no fixed version is available for xmldom.
References8
- github.com/xmldom/xmldom/commit/cba1321218b069182695813fa756565…
- github.com/xmldom/xmldom/commit/d8212e632507eaf1d9f609657dd4c56…
- github.com/xmldom/xmldom/pull/1043
- github.com/xmldom/xmldom/pull/1050
- github.com/xmldom/xmldom/releases/tag/0.8.14
- github.com/xmldom/xmldom/releases/tag/0.9.11
- github.com/xmldom/xmldom/security/advisories/GHSA-4w3w-2rp5-g8jm
- github.com/xmldom/xmldom/security/advisories/GHSA-4w3w-2rp5-g8jm
Metrics
- CVSS 4.0
-
8.7
HIGH
Score source: 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 50 · as of 8 November 2026
- CWE
- CWE-91
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.