What is CVE-2026-49978?

CVE-2026-49978 is a medium-severity vulnerability in Cure53 Dompurify, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-14.

How severe is CVE-2026-49978?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Cure53 Dompurify

CVE-2026-49978

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Prior to 3.4.7, DOMPurify IN_PLACE sanitization could skip shadow contents attached to an element inside <template>.content, allowing attacker-controlled markup such as event handlers, JavaScript URLs, or scripts to survive and execute when an application cloned and inserted the sanitized template. This issue is fixed in version 3.4.7.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-07-14 · last modified 2026-07-21.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.6th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Cure53 Dompurify — versions < 3.4.6

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/cure53/DOMPurify/security/advisories/GHSA-rp9w-3fw7-7cwq (Exploit, Vendor Advisory)
github.com/cure53/DOMPurify/commit/ca30f070c360df162a3e3848e80e6fd3c9e74bff (Patch)
github.com/cure53/DOMPurify/releases/tag/3.4.7 (Release Notes)

Frequently asked questions

What is CVE-2026-49978?: CVE-2026-49978 is a medium-severity vulnerability in Cure53 Dompurify, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-14.
How severe is CVE-2026-49978?: Medium severity. CVSS v3 base score is 6.1 out of 10.