CVE-2026-41240: DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG

Q: How do I fix CVE-2026-41240?

dompurify: upgrade to 3.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-41240 being exploited?

CVE-2026-41240 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-2026-41240 affect?

CVE-2026-41240 affects dompurify. Severity is medium (CVSS 6.1). DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early

Q: How urgent is CVE-2026-41240?

Priority 32/100. Public exploit reference

Routine

MEDIUM 6.1UPGRADE

CVE-2026-41240 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. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early exit for FORBID_ATTR at line 1214. The same fix was not applied to FORBID_TAGS. At line 1118-1123, when EXTRA_ELEMENT_HANDLING.tagCheck returns true, the short-circuit evaluation skips the FORBID_TAGS check en

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	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-79, CWE-183
Published	2026-04-23
Last modified	2026-10-26

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

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-23 16:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

cure53 dompurify UPGRADE

Affected: < 3.4.0

Fixed in: 3.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.4.0 (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-2026-41240?

dompurify: upgrade to 3.4.0. Exact commands for each OS are on this page.

Is CVE-2026-41240 being exploited?

CVE-2026-41240 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-2026-41240 affect?

CVE-2026-41240 affects dompurify. Severity is medium (CVSS 6.1). DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG. Versions prior to 3.4.0 have an inconsistency between FORBID_TAGS and FORBID_ATTR handling when function-based ADD_TAGS is used. Commit c361baa added an early

How urgent is CVE-2026-41240?

Priority 32/100. 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-2026-49978 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

References

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