# CVE-2026-116804: DOMPurify SAFE_FOR_TEMPLATES bypass via shadow root content

Source: https://junglewise.ai/threats/cve-2026-116804-dompurify-from-3-4-4-before-3-4-17-contains-a-safe-for-templates  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-116804 · Severity: medium · CVSS 6.1 · Published 2026-10-27

DOMPurify is a JavaScript library that sanitizes HTML and removes potentially malicious code to prevent cross-site scripting attacks. When configured with SAFE_FOR_TEMPLATES mode and certain DOM-output options, an attacker can craft malicious input containing shadow DOM elements that allows template expressions like {{...}} to survive sanitization. If the application then evaluates this content as a template, attackers can execute arbitrary JavaScript code in the victim's browser.

Technologies: [Cure53 DOMPurify](https://junglewise.ai/threats/technologies/cure53-dompurify). Vendors: [Cure53](https://junglewise.ai/threats/vendors/cure53).

## Quick answers

**Is CVE-2026-116804 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116804 being exploited in the wild.

**How severe is CVE-2026-116804?** Medium severity, with a CVSS score of 6.1, published 27 October 2026.

**Which products and versions are affected?** Cure53 DOMPurify 3.4.4 before 3.4.17.

**Is there a fix for CVE-2026-116804?** Yes: fixed in 3.4.17. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-116804 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-116804?** Check whether you run Cure53 DOMPurify at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 3.4.17

## Technical details

The vulnerability is a SAFE_FOR_TEMPLATES bypass affecting DOMPurify's post-walk sanitization pass (_scrubTemplateExpressions), which fails to recurse into attached shadow roots when normalizing text nodes. An attacker can split template expressions across text nodes separated by disallowed elements; after those elements are removed during sanitization, the text fragments merge into a complete, executable expression. This requires the application to use RETURN_DOM, RETURN_DOM_FRAGMENT, or IN_PLACE modes, pass a DOM node with an already-attached shadow root, and subsequently evaluate the shadow root content as a template.

## Affected products

- Cure53 DOMPurify 3.4.4 before 3.4.17

## Timeline

- 2026-10-12: disclosed
- 2026-10-27: advisory

## References

- [https://github.com/cure53/DOMPurify/security/advisories/GHSA-cg2g-xh64-v4q7](https://github.com/cure53/DOMPurify/security/advisories/GHSA-cg2g-xh64-v4q7)
- [https://www.vulncheck.com/advisories/dompurify-from-3.4.4-before-3.4.17-safe-for-templates-bypass-via-shadow-root-content](https://www.vulncheck.com/advisories/dompurify-from-3.4.4-before-3.4.17-safe-for-templates-bypass-via-shadow-root-content)

## Related threats

- [DOMPurify DOM XSS in IN_PLACE hook-detached subtrees](https://junglewise.ai/threats/cve-2026-116803-dompurify-before-3-4-17-contains-a-cross-site-scripting)
- [DOMPurify cross-site scripting in SMIL attributeName guard bypass](https://junglewise.ai/threats/cve-2026-116802-dompurify-before-3-4-17-contains-a-cross-site-scripting)
- [DOMPurify SAFE_FOR_TEMPLATES bypass in shadow root content](https://junglewise.ai/threats/dompurify-safe-for-templates-bypass-split-template-expressions-survive-c23665cf)
- [DOMPurify IN_PLACE event handler bypass when hook removes parent or sibling](https://junglewise.ai/threats/dompurify-in-place-hook-that-removes-a-parent-or-sibling-leaves-the-3ea5d18f)
- [DOMPurify SMIL attributeName=href guard bypass in XHTML mode](https://junglewise.ai/threats/dompurify-smil-attributename-href-guard-is-skipped-when-parser-media-15a5efd2)