What is CVE-2026-41240?

CVE-2026-41240 is a medium-severity vulnerability in Cure53 Dompurify, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-23.

How severe is CVE-2026-41240?

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

XSS in Cure53 Dompurify

CVE-2026-41240

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 entirely. This allows forbidden elements to survive sanitization with their attributes intact. Version 3.4.0 patches the issue.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.003 (23.7th percentile) — read the EPSS interpretation.

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.

Affected products

Cure53 Dompurify — versions < 3.4.0

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Patch, Mitigation, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (Product, x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-41240?: CVE-2026-41240 is a medium-severity vulnerability in Cure53 Dompurify, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-23.
How severe is CVE-2026-41240?: Medium severity. CVSS v3 base score is 6.1 out of 10.