Rapid7’s 2026 Global Cybersecurity Summit is now available on-demand.Watch sessions.
Rapid7

vulnerability

MFSA2025-59 Firefox: Security Vulnerabilities fixed in Firefox ESR 140.1 (CVE-2025-8034)

Severity
9
CVSS
(AV:N/AC:M/Au:N/C:C/I:C/A:C)
Published
Jul 22, 2025
Added
Jul 23, 2025
Modified
Apr 15, 2026

Description

Memory safety bugs present in Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird ESR 128.12, Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

Solution

mozilla-firefox-esr-upgrade-140_1
Title
Rapid7 Labs

2026 Global Threat Landscape Report

The predictive window has collapsed. Exploitation follows disclosure in days. See how attackers are accelerating and how to stay ahead.