Tampering by prototype polution in DOMPurify

Vulnerability Description

DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. It has been discovered that malicious HTML using special nesting techniques can bypass the depth checking added to DOMPurify in recent releases. It was also possible to use Prototype Pollution to weaken the depth check. This renders dompurify unable to avoid cross site scripting (XSS) attacks. This issue has been addressed in versions 2.5.4 and 3.1.3 of DOMPurify. All users are advised to upgrade. There are no known workarounds for this vulnerability.

References

• https://github.com/cure53/DOMPurify/security/advisories/GHSA-mmhx-hmjr-r674
• https://github.com/cure53/DOMPurify/commit/1e520262bf4c66b5efda49e2316d6d1246ca7b21
• https://github.com/cure53/DOMPurify/commit/26e1d69ca7f769f5c558619d644d90dd8bf26ebc