medium advisory March 24, 2026

Mozilla Firefox and Thunderbird Graphics Text Component Vulnerability (CVE-2026-4719)

CVE-2026-4719 describes an incorrect boundary condition in the Graphics: Text component of Mozilla Firefox and Thunderbird, potentially leading to a denial-of-service condition in vulnerable versions.

CVE-2026-4719 is a security vulnerability affecting Mozilla Firefox and Thunderbird. The vulnerability stems from incorrect boundary conditions within the Graphics: Text component. Specifically, Firefox versions prior to 149, Firefox ESR versions prior to 140.9, Thunderbird versions prior to 149, and Thunderbird ESR versions prior to 140.9 are affected. Successful exploitation of this vulnerability could potentially lead to a denial-of-service condition by crashing the application. This…

Detection coverage 2

Firefox/Thunderbird Crash Report

low

Detects crash reports generated by Firefox or Thunderbird, which could indicate exploitation of CVE-2026-4719 or other vulnerabilities.

sigma tactics: availability techniques: T1499 sources: file_event, windows

Detect Firefox or Thunderbird versions below fixed versions

medium

Detects vulnerable versions of Firefox or Thunderbird based on process execution metadata.

sigma tactics: vulnerability sources: process_creation, windows

Detection queries are kept inside the platform. Get full rules →