CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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 affects Firefox < 149.0.2 and Firefox ESR < 140.9.1.
Analysis
Multiple memory corruption vulnerabilities in Mozilla Firefox (< 149.0.2) and Firefox ESR (< 140.9.1) enable unauthenticated remote code execution with critical CVSS 9.8 severity. These memory safety bugs-including CWE-787 out-of-bounds write issues-affect both standard and Extended Support Release channels, with Mozilla confirming evidence of memory corruption exploitable for arbitrary code execution. …
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Remediation
Within 24 hours: Communicate mandatory upgrade requirement to all users and identify organizational Firefox deployment scope (standard and ESR versions). Within 7 days: Deploy Firefox 149.0.2 or later (standard) and Firefox ESR 140.9.1 or later via update management systems; verify deployment completion. …
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External POC / Exploit Code
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EUVD-2026-19614