# CVE-2026-65904: DOMPurify through 3.3.3 Cross-Site Scripting via IN_PLACE mode

> DOMPurify fails to sanitize cross-realm DOM elements in IN_PLACE mode, allowing attackers to inject XSS payloads.

- **Severity:** Low 2.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Jul 2026
- **Updated:** 24 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-65904, GHSA-4w3q-35jp-p934, UBUNTU-CVE-2026-65904

## What is CVE-2026-65904?

CVE-2026-65904 is a low-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-754 (Improper Check for Unusual or Exceptional Conditions)

## Which versions are affected by CVE-2026-65904?

It affects 1 product.


Products: Cure53 Dompurify.

## How do I fix CVE-2026-65904?

Upgrade to a fixed version.

## Is CVE-2026-65904 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-65904 exists.

## Other vulnerabilities in cure53 DOMPurify

- [CVE-2024-47875](https://insights.sbomify.com/CVE-2024-47875/): DOMPurify nesting-based mXSS (critical 10.0)
- [CVE-2024-48910](https://insights.sbomify.com/CVE-2024-48910/): DOMPurify vulnerable to tampering by prototype polution (critical 9.1)
- [CVE-2026-47423](https://insights.sbomify.com/CVE-2026-47423/): DOMPurify XSS via `selectedcontent` re-clone (high 8.2)
- [CVE-2024-45801](https://insights.sbomify.com/CVE-2024-45801/): Tampering by prototype polution in DOMPurify (high 7.3)
- [CVE-2026-49978](https://insights.sbomify.com/CVE-2026-49978/): DOMPurify IN_PLACE Sanitization Bypass via Attached Shadow Root Inside <template>.content (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-65904 and fix it if it is affected.

What it is: CVE-2026-65904 is a low-severity cross-site scripting vulnerability in cure53 DOMPurify, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-65904 exists.

Affected product: cure53 DOMPurify. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-65904/ (Markdown: https://insights.sbomify.com/CVE-2026-65904/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-65904
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-65904
- OSV: https://osv.dev/vulnerability/CVE-2026-65904

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-65904/
Summaries are generated and may contain mistakes; the official description above is the record.