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CVE-2026-83613: xmldom: Quadratic-time attribute deduplication

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-01 · updated 2026-09-08
• Weakness: CWE-407

Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom version 0.6.0 and earlier, DOMHandler.startElement in lib/dom-parser.js inserts every parsed attribute through setAttributeNode, while NamedNodeMap.setNamedItem in lib/dom.js calls the linear getNamedItem or getNamedItemNS lookup for each insertion. A well-formed element with many distinct attributes therefore requires quadratic comparisons during DOMParser.parseFromString() and can stall a Node.js event loop before application validation. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

Affected products

• xmldom: through 0.6.0; from 0.9.0, < 0.9.12; from 0.7.0, < 0.8.15

References

• https://github.com/xmldom/xmldom/commit/2c548f200cfec991cd5846627ef8f03542309213
• https://github.com/xmldom/xmldom/commit/cfb09b5dbeb035fdfedc9f01e2bbaf226bf47cf3
• https://github.com/xmldom/xmldom/pull/1071
• https://github.com/xmldom/xmldom/pull/1072
• https://github.com/xmldom/xmldom/releases/tag/0.8.15
• https://github.com/xmldom/xmldom/releases/tag/0.9.12
• https://github.com/xmldom/xmldom/security/advisories/GHSA-8344-3jmq-59r6
• https://github.com/xmldom/xmldom/security/advisories/GHSA-27p8-2357-5qqv

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