CVE-2026-4720

CWE-120 — Classic Buffer Overflow13 documents9 sources
Severity
9.8CRITICAL
EPSS
0.0%
top 93.89%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
3
Mozilla FirefoxMozilla Firefox ESRMozilla Thunderbird
Timeline
PublishedMar 24

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 affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitability: 3.9 | Impact: 5.9

Affected Packages7 packages

▶CVEListV5mozilla/firefoxunspecified — 149
▶NVDmozilla/firefox< 140.9.0+1
▶CVEListV5mozilla/firefox_esrunspecified — 140.9
▶CVEListV5mozilla/thunderbirdunspecified — 149+1
▶NVDmozilla/thunderbird< 140.9.0+1

🔴Vulnerability Details

3
CVEList
Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149↗2026-03-24
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OSV
CVE-2026-4720: Memory safety bugs present in Firefox ESR 140↗2026-03-24
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GHSA
GHSA-h6r3-p5gv-5qgc: Memory safety bugs present in Firefox ESR 140↗2026-03-24
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📋Vendor Advisories

6
Red Hat
firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149↗2026-03-24
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Debian
CVE-2026-4720: firefox - Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox ...↗2026
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Mozilla
Mozilla Foundation Security Advisory 2026-23: CVE-2026-4720↗
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Mozilla
Mozilla Foundation Security Advisory 2026-24: CVE-2026-4720↗
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Mozilla
Mozilla Foundation Security Advisory 2026-20: CVE-2026-4720↗
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🕵️Threat Intelligence

1
Wiz
CVE-2026-4720 Impact, Exploitability, and Mitigation Steps | Wiz↗
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💬Community

1
Bugzilla
CVE-2026-4720 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149↗2026-03-24
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