High [CVE-2026-49978] Cross-site scripting vulnerability allows code execution

DOMPurify is a DOM-only cross-site scripting sanitizer for HTML, MathML, and SVG.

Prior to 3.4.7, DOMPurify IN_PLACE sanitization could skip shadow contents attached to an element inside.content, allowing attacker-controlled markup such as event handlers, JavaScript URLs, or scripts to survive and execute when an application cloned and inserted the sanitized template. This issue is fixed in version 3.4.7.

When performing in-place sanitization, DOMPurify could fail to properly process content within shadow DOM elements attached to a `.content`.

This oversight allows an attacker to embed malicious code, such as JavaScript, which could then execute when the sanitized template is used by an application, potentially leading to unauthorized actions or information disclosure. This vulnerability in DOMPurify is rated as Important as it allows for cross-site scripting (XSS) attacks.

This could lead to unauthorized actions or information disclosure in Red Hat products that utilize DOMPurify for sanitizing untrusted HTML, MathML, or SVG. Red Hat severity: Important — CVSS 8.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N).

Weakness: CWE-79.

Affected products named by the advisory: Cryostat 4 on RHEL 9; Red Hat AMQ Broker 7.13.6; Red Hat AMQ Broker 7.14.1; Red Hat build of Apicurio Registry 3.3.1; and 33 more.