CVE-2026-65903: dompurify — Exploit

Description

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output.

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CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-697 CWE-697

Affected Products

Vendor	Product	Versions
cure53	dompurify	< 3.4.0

References

Exploits

https://github.com/cure53/DOMPurify/security/advisories/GHSA-39q2-94rc-95cp

Other References

https://www.vulncheck.com/advisories/dompurify-before-add-tags-function-bypasses-forbid-tags

Frequently Asked Questions

What is CVE-2026-65903? +

DOMPurify before 3.4.0 contains a logic error in the ADD_TAGS function where short-circuit evaluation allows forbidden tags to bypass FORBID_TAGS restrictions. Attackers can craft input containing tags listed in FORBID_TAGS that are also added via ADD_TAGS function, causing them to be retained in sanitized output. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-65903? +

CVE-2026-65903 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-65903? +

CVE-2026-65903 affects products from cure53, specifically: dompurify. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-65903? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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