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CVE-2026-4720

CRITICAL
9.8
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-4720
State
PUBLISHED
Assigner
mozilla
Reserved
2026-03-23 23:22 UTC
Published
2026-03-24 12:30 UTC
Last updated
2026-07-15 00:49 UTC
Primary CWE
CWE-120
CWE-120 Buffer Copy without Checking Size of Input ('Classic…
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 — 140.9 ≤ 140.*, 149 ≤ *
Mozilla Thunderbird — 140.9 ≤ 140.*, 149 ≤ *
Weakness (CWE)
CWESourceDescription
CWE-120 adp CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-120 adp Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CVSS scores (2)
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
7.5 HIGH 3.1 adp CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
References (5)
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