Is This vulnerability exploited in the wild?

No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

How severe is This vulnerability?

Critical severity, with a CVSS score of 4, published 22 October 2026.

Which products and versions are affected?

Cure53 DOMPurify 3.4.4 through 3.4.16; DOMPurify 3.4.4 through 3.4.16; dompurify (npm) >= 3.4.4, <= 3.4.16, SEMVER:introduced=3.4.4,fixed=3.4.17.

Is there a fix for This vulnerability?

Yes. dompurify (npm): upgrade to 3.4.17 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is This vulnerability attacked?

It is attacked over the network, in a software library.

Check whether you run Cure53 DOMPurify, DOMPurify or dompurify (npm) 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.

DOMPurify SAFE_FOR_TEMPLATES bypass in shadow root content

Q: Is there a fix for This vulnerability?

Yes. dompurify (npm): upgrade to 3.4.17 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is This vulnerability attacked?

It is attacked over the network, in a software library.

Q: Am I affected?

Check whether you run Cure53 DOMPurify, DOMPurify or dompurify (npm) 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.

Severity: critical · CVSS 4 · Published 2026-10-22

DOMPurify is a JavaScript library that sanitizes HTML to prevent XSS attacks. When configured to protect template expressions (like ${...}), it fails to clean template syntax inside shadow DOM content, allowing attackers to inject malicious code that a downstream template engine will execute as code. This can lead to stolen data or account takeover in web applications.

Technologies: Cure53 DOMPurify, dompurify (npm). Vendors: Cure53, npm.

Quick answers

Is This vulnerability exploited in the wild?: No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?: Critical severity, with a CVSS score of 4, published 22 October 2026.
Which products and versions are affected?: Cure53 DOMPurify 3.4.4 through 3.4.16; DOMPurify 3.4.4 through 3.4.16; dompurify (npm) >= 3.4.4, <= 3.4.16, SEMVER:introduced=3.4.4,fixed=3.4.17.
Is there a fix for This vulnerability?: Yes. dompurify (npm): upgrade to 3.4.17 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?: It is attacked over the network, in a software library.
Am I affected?: Check whether you run Cure53 DOMPurify, DOMPurify or dompurify (npm) 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

dompurify (npm): upgrade to 3.4.17 or later
```
npm install dompurify@3.4.17
```

Technical details

When SAFE_FOR_TEMPLATES is enabled with DOM-returning modes (IN_PLACE, RETURN_DOM, or RETURN_DOM_FRAGMENT), the post-walk safety check _scrubTemplateExpressions does not recurse into attached shadow roots, only into <template> elements. An attacker can split a template expression (e.g., "${alert(1)}") across text nodes separated by disallowed elements; when the disallowed elements are stripped during sanitization, the fragments become adjacent and merge into a complete expression that survives. This requires an attacker-supplied DOM node with an attached shadow root and downstream template evaluation.

Affected products

Cure53 DOMPurify 3.4.4 through 3.4.16

Timeline

2026-10-22: disclosed

References

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