Back to overview

CVE-2026-5731

CRITICAL
9.8
CVSS 3.1
Description
Memory safety bugs present in Firefox ESR 115.34.0, 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 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

Metadata

CVE ID
CVE-2026-5731
State
PUBLISHED
Assigner
mozilla
Reserved
2026-04-07 12:43 UTC
Published
2026-04-07 12:43 UTC
Last updated
2026-05-26 18:14 UTC
Primary CWE
CWE-119
CWE-119 Improper Restriction of Operations within the Bounds…
Vendor / Product
Mozilla / Firefox
Sources
cve.org  ·  NVD

Severity & Metrics

9.8 CRITICAL CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC — CISA Coordinator
Exploitation
none
Automatable
no
Tech. Impact
total
Affected products (2)
VendorProductPlatformVersions
Mozilla Firefox — 115.34.1 ≤ 115.*, 140.9.1 ≤ 140.*, 149.0.2 ≤ *
Mozilla Thunderbird — 140.9.1 ≤ 140.*, 149.0.2 ≤ *
Weakness (CWE)
CWESourceDescription
CWE-119 adp CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
CVSS scores (1)
ScoreSeverityVersionSourceVector
9.8 CRITICAL 3.1 adp CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References (6)
Back to overview