CVE-2026-5734

CRITICAL

Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2

Title source: cna
STIX 2.1

Description

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 was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

References (32)

Core 32
Core References
Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022369%2C2023026%2C2023545%2C2023555%2C2023958%2C2025422%2C2025468%2C2025492%2C2025505

Scores

CVSS v3 9.8
EPSS 0.0033
EPSS Percentile 25.4%
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 CWE-787
Status published
Products (12)
mozilla/firefox < 140.9.1
mozilla/firefox < 149.0.2
Mozilla/Firefox 140.9.1 - 140.*
Mozilla/Firefox 149.0.2
Mozilla/Firefox unspecified - 149.0.2
Mozilla/Firefox ESR unspecified - 140.9.1
mozilla/thunderbird < 140.9.1
mozilla/thunderbird < 149.0.2
Mozilla/Thunderbird 140.9.1 - 140.*
Mozilla/Thunderbird 149.0.2
... and 2 more
Published Apr 07, 2026
Tracked Since Apr 07, 2026