CVE-2026-65903 DOMPurify before 3.4.0 ADD_TAGS Function Bypasses FORBID_TAGS
Attackers can bypass DOMPurify's FORBID_TAGS restrictions by using ADD_TAGS, allowing forbidden HTML tags to remain in sanitized output.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-65903?
CVE-2026-65903 is a medium-severity vulnerability in cure53 DOMPurify, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-697
Which versions are affected by CVE-2026-65903?
2 open source packages ship an affected version, including dompurify. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
dompurify npm | All versions | 3.4.0 |
dompurify npm | All versions | 3.4.0 |
Products include Cure53 Dompurify.
How do I fix CVE-2026-65903?
Upgrade dompurify to 3.4.0 or later.
Is CVE-2026-65903 being exploited?
There is no known exploitation of CVE-2026-65903 in the wild and no public exploit code.
Other vulnerabilities in cure53 DOMPurify
- CVE-2024-47875 DOMPurify nesting-based mXSS
- CVE-2024-48910 DOMPurify vulnerable to tampering by prototype polution
- CVE-2026-47423 DOMPurify XSS via `selectedcontent` re-clone
- CVE-2024-45801 Tampering by prototype polution in DOMPurify
- CVE-2026-49978 DOMPurify IN_PLACE Sanitization Bypass via Attached Shadow Root Inside <template>.content
Sources
Also known as CLEANSTART-2026-BG16749, CLSA-2026-1784596278, CLSA-2026-1784596303, DEBIAN-CVE-2026-65903, ECHO-c3eb-b997-34cf, GHSA-39q2-94rc-95cp and 14 more.