Undefined Behavior in Firefox Core and HTML Components
CVE-2026-2771

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox; Firefox Esr; Thunderbird
Vendor: CVE Published:; 24 February 2026

What is CVE-2026-2771?

This vulnerability arises from undefined behavior in the Document Object Model (DOM) within the Core and HTML components of Firefox. The issue impacts various versions, allowing potential security risks in web browser functionality. Affected versions include Firefox prior to 148 along with specific Extended Support Release (ESR) versions, creating an urgent need for users to update to secure versions to mitigate potential exploitation.

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