CVE-2026-4720

CRITICAL

Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149

Title source: cna
STIX 2.1

Description

Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

References (33)

Core 33
Core References
Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2004652%2C2019372%2C2021922%2C2022567%2C2022733

Scores

CVSS v3 9.8
EPSS 0.0042
EPSS Percentile 34.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-120
Status published
Products (12)
mozilla/firefox < 140.9.0
mozilla/firefox < 149.0
Mozilla/Firefox 140.9 - 140.*
Mozilla/Firefox 149
Mozilla/Firefox unspecified - 149
Mozilla/Firefox ESR unspecified - 140.9
mozilla/thunderbird < 140.9.0
mozilla/thunderbird < 149.0
Mozilla/Thunderbird 140.9 - 140.*
Mozilla/Thunderbird 149
... and 2 more
Published Mar 24, 2026
Tracked Since Mar 24, 2026