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Medium, CVSS 5.3amended

DOMPurify USE_PROFILES prototype pollution allows event handlers

CVE-2026-65913GHSA-cj63-jhhr-wcxv

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (dompurify 3.3.2), redeploy, then verify what is actually installed.

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

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N · score source
EPSS
  • CVE-2026-65913: 0.32% estimated exploitation activity in the next 30 days; percentile 24.75 (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 When USEPROFILES is enabled, DOMPurify rebuilds ALLOWEDATTR as a plain array before populating it with the requested allowlists. Because the sanitizer still looks up attributes via ALLOWEDATTR[lcName], any Array.prototype property that is polluted also counts as an allowlisted attribute. An attacker who can set Array.prototype.onclick = true (or a runtime already subject to prototype pollution) can thus force DOMPurify to keep event handlers such as onclick even when they are normally forbidden. The provided PoC sanitizes <img onclick=... with USEPROFILES and adds the sanitized output to the DOM; the polluted prototype allows the event handler to survive and execute, turning what should be a blocklist into a silent XSS vector. Impact Prototype pollution makes DOMPurify accept dangerous event handler attributes, which bypasses the sanitizer and results in DOM-based XSS once the sanitized markup is rendered. Credits Identified by Cantina’s Apex (https://www.cantina.security).

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-cj63-jhhr-wcxv

  2. Revision 2 · amended ·

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

  3. Revision 1 · created ·

    Published from osv record GHSA-cj63-jhhr-wcxv

Agent brief

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# Patch Next advisory brief: CVE-2026-65913

Advisory: DOMPurify USE_PROFILES prototype pollution allows event handlers
IDs: CVE-2026-65913, GHSA-cj63-jhhr-wcxv
Record: https://patchnext.com/advisories/cve-2026-65913 (revision 3, source checked 26 Oct 2026, 12:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: dompurify 3.3.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm dompurify: affected <= 3.3.1; fixed in 3.3.2

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on dompurify.
- 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://osv.dev/vulnerability/GHSA-cj63-jhhr-wcxv (OSV record GHSA-cj63-jhhr-wcxv lists affected ranges: npm dompurify >=0 <3.3.2 (fixed))
- Verified: https://github.com/advisories/GHSA-cj63-jhhr-wcxv (GitHub-reviewed advisory GHSA-cj63-jhhr-wcxv lists affected ranges: npm dompurify >=0 <=3.3.1)

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