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CVE-2026-49978

MEDIUMCVSS 6.1/10EPSS 0.54%

Last modified

CVE-2026-49978 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. 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. EPSS estimates a 0.54% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS 4.0
6.3/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.54%

41.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Cure53Dompurify< 3.4.7

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is 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.
How severe is CVE-2026-49978?
CVE-2026-49978 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.54% probability of exploitation in the next 30 days.
How do I fix CVE-2026-49978?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST