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High, CVSS 8.7amended

xmldom: Attribute name injection via setAttribute() bypasses requireWellFormed

CVE-2026-83605GHSA-4w3w-2rp5-g8jm

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
    >= 0.9.0, <= 0.9.10>= 0.7.0, <= 0.8.13
    Fixed in
    0.9.11, 0.8.14

  • 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:H/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-83605: 0.61% estimated exploitation activity in the next 30 days; percentile 49.35 (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 Element.setAttribute() in @xmldom/xmldom bypasses attribute name validation by calling the private createAttribute(name) method, which performs no validation. The public createAttribute() method correctly validates names against an anchored QName pattern, but setAttribute() never uses it. The serializer escapes attribute values but trusts attribute names, allowing an attacker to inject additional attributes (including event handlers) into serialized output. The requireWellFormed: true option did not catch this. Details Element.setAttribute(name, value) creates attribute nodes by calling the private createAttribute(name) method, which performs no validation on the name parameter. In contrast, the public Document.createAttribute(name) method validates the name against the QName production before creating the attribute node. The result is a two-tier validation system where the most commonly used API (setAttribute) takes the unvalidated path: - doc.createAttribute("bad name") —…

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

    Amended from ghsa record GHSA-4w3w-2rp5-g8jm

  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-4w3w-2rp5-g8jm

  4. Revision 1 · created ·

    Published from ghsa record GHSA-4w3w-2rp5-g8jm

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-2026-83605

Advisory: xmldom: Attribute name injection via setAttribute() bypasses requireWellFormed
IDs: CVE-2026-83605, GHSA-4w3w-2rp5-g8jm
Record: https://patchnext.com/advisories/cve-2026-83605 (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 0.9.11, 0.8.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @xmldom/xmldom: affected >= 0.9.0, <= 0.9.10; >= 0.7.0, <= 0.8.13; fixed in 0.9.11, 0.8.14
- 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-4w3w-2rp5-g8jm (GitHub-reviewed advisory GHSA-4w3w-2rp5-g8jm lists affected ranges: npm @xmldom/xmldom >=0.9.0 =0.7.0 =0 <=0.6.0)
- Verified: https://osv.dev/vulnerability/GHSA-4w3w-2rp5-g8jm (OSV record GHSA-4w3w-2rp5-g8jm lists affected ranges: npm @xmldom/xmldom >=0.9.0 =0.7.0 =0 <=0.6.0)

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