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High, CVSS 8.7amended

xmldom: Quadratic-time attribute deduplication

CVE-2026-83613GHSA-8344-3jmq-59r6

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm @xmldom/xmldom

    Affected
    >= 0.7.0, <= 0.8.14>= 0.9.0, <= 0.9.11
    Fixed in
    0.9.12, 0.8.15

  • npm xmldom

    Affected
    <= 0.6.0
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.7 · 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 · score source
EPSS
  • CVE-2026-83613: 0.60% estimated exploitation activity in the next 30 days; percentile 48.94 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary xmldom builds the attribute collection of every parsed element by inserting attributes one at a time into a DOM NamedNodeMap. Each insertion first performs a linear scan of all already-inserted attributes to enforce the DOM uniqueness rule (no two attributes with the same qualified name / namespace+local-name). Parsing an element that carries M distinct attributes therefore costs 1 + 2 + … + M = O(M²) comparisons. Because the trigger is simply "one element with many attributes", the attack payload is a fully well-formed XML document. No malformed markup, no error recovery, and no non-default parser options are involved — parsing completes silently with zero warning/error/fatalError events. An attacker who can submit a modest, highly compressible document (a single element with tens of thousands of attributes, ~340 KB uncompressed) can consume seconds of single-threaded CPU per request, enabling an unauthenticated denial of service. This is distinct from the known…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-8344-3jmq-59r6

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-8344-3jmq-59r6

  4. Revision 1 · created ·

    Published from ghsa record GHSA-8344-3jmq-59r6

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-83613

Advisory: xmldom: Quadratic-time attribute deduplication
IDs: CVE-2026-83613, GHSA-8344-3jmq-59r6
Record: https://patchnext.com/advisories/cve-2026-83613 (revision 4, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: @xmldom/xmldom 0.9.12, 0.8.15. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @xmldom/xmldom: affected >= 0.7.0, <= 0.8.14; >= 0.9.0, <= 0.9.11; fixed in 0.9.12, 0.8.15
- npm xmldom: affected <= 0.6.0

## Suggested inspection (read-only)
- `npm ls @xmldom/xmldom --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls xmldom --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @xmldom/xmldom, xmldom.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8344-3jmq-59r6 (GitHub-reviewed advisory GHSA-8344-3jmq-59r6 lists affected ranges: npm @xmldom/xmldom >=0.7.0 =0.9.0 =0 <=0.6.0)
- Verified: https://osv.dev/vulnerability/GHSA-8344-3jmq-59r6 (OSV record GHSA-8344-3jmq-59r6 lists affected ranges: npm @xmldom/xmldom >=0.7.0 =0.9.0 =0 <=0.6.0)

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