CVE-2026-49978: DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG

Q: How do I fix CVE-2026-49978?

dompurify: upgrade to 3.4.7. Exact commands for each OS are on this page.

Q: Is CVE-2026-49978 being exploited?

CVE-2026-49978 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-49978 affect?

CVE-2026-49978 affects dompurify. Severity is medium (CVSS 6.1). 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 .content, allowing attacker-controlled mark

Routine

MEDIUM 6.1UPGRADE

CVE-2026-49978 is a medium-severity flaw (CVSS 6.1) affecting dompurify. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 66%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-07-14
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc. · Vendor: cure53

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 21:17 UTCPublished CVE record published
2026-10-24 21:10 UTCUpdated Record last modified

cure53 dompurify UPGRADE

Affected: < 3.4.7

Fixed in: 3.4.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy dompurify || rpm -q dompurify || dompurify --version

2. UPGRADE to 3.4.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade dompurify

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade dompurify

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49978?

dompurify: upgrade to 3.4.7. Exact commands for each OS are on this page.

Is CVE-2026-49978 being exploited?

CVE-2026-49978 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49978 affect?

CVE-2026-49978 affects dompurify. Severity is medium (CVSS 6.1). 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 mark

How urgent is CVE-2026-49978?

Priority 35/100. Public exploit reference

Related CVEs

CVE-2026-47423 HIGH 8.2 DOWNGRADE DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG
CVE-2026-49458 MEDIUM 6.1 UPGRADE DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG
CVE-2026-49459 MEDIUM 6.1 UPGRADE DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG
CVE-2026-65898 HIGH 7.2 UPGRADE DOMPurify before 3.4.11 fails to clone the ALLOWED_ATTR allowlist when setConfig() is used with an uponSanitiz
CVE-2026-65899 MEDIUM 6.1 UPGRADE DOMPurify 3.0.0 before 3.4.9 does not reset the retained Trusted Types policy when clearConfig() is called, so

References

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