CVE-2026-4371

EUVD-2026-15023
A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.4 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 28.77%
Affected Products (NVD)
VendorProductVersion
mozillathunderbird_esr
𝑥
< 140.9.0
mozillathunderbird
𝑥
< 149.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
Red HatRed Hat Enterprise Linux 10
0:140.9.0-1.el10_1 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 10.0 Extended Update Support
0:140.9.0-1.el10_0 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8
0:140.9.0-1.el8_10 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.2 Advanced Update Support
0:140.9.0-1.el8_2 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
0:140.9.0-1.el8_4 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
0:140.9.0-1.el8_4 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
0:140.9.0-1.el8_6 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Service
0:140.9.0-1.el8_6 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutions
0:140.9.0-1.el8_6 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Service
0:140.9.0-1.el8_8 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutions
0:140.9.0-1.el8_8 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 9
0:140.9.0-1.el9_7 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutions
0:140.9.0-1.el9_0 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutions
0:140.9.0-1.el9_2 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 9.4 Extended Update Support
0:140.9.0-1.el9_4 ≤
𝑥
< *
ADP
Red HatRed Hat Enterprise Linux 9.6 Extended Update Support
0:140.9.0-1.el9_6 ≤
𝑥
< *
ADP
Debian logo
Debian Releases
Debian Product
Codename
thunderbird
bookworm
1:140.12.0esr-1~deb12u1
fixed
bookworm (security)
1:140.13.0esr-2~deb12u1
fixed
bullseye
vulnerable
bullseye (security)
1:140.12.0esr-1~deb11u1
fixed
forky
1:140.12.0esr-1
fixed
sid
1:140.13.0esr-2
fixed
trixie
1:140.12.0esr-1~deb13u1
fixed
trixie (security)
1:140.13.0esr-2~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
jammy
not-affected
noble
not-affected
questing
not-affected
resolute
not-affected
mozjs102
jammy
ignored
noble
ignored
questing
dne
resolute
dne
mozjs115
jammy
dne
noble
ignored
questing
dne
resolute
dne
mozjs38
bionic
needs-triage
jammy
dne
noble
dne
questing
dne
resolute
dne
mozjs52
bionic
ignored
focal
ignored
jammy
dne
noble
dne
questing
dne
resolute
dne
mozjs68
focal
ignored
jammy
dne
noble
dne
questing
dne
resolute
dne
mozjs78
jammy
ignored
noble
dne
questing
dne
resolute
dne
mozjs91
jammy
ignored
noble
dne
questing
dne
resolute
dne
thunderbird
jammy
needed
noble
not-affected
questing
not-affected
resolute
not-affected
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
MozillaThunderbird
suse enterprise desktop 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise sap 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise server 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise workstation 15 SP7
140.9.0-150200.8.263.1
fixed
MozillaThunderbird-translations-common
suse enterprise desktop 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise sap 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise server 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise workstation 15 SP7
140.9.0-150200.8.263.1
fixed
MozillaThunderbird-translations-other
suse enterprise desktop 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise sap 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise server 15 SP7
140.9.0-150200.8.263.1
fixed
suse enterprise workstation 15 SP7
140.9.0-150200.8.263.1
fixed
Red Hat logo
Red Hat Enterprise Linux Releases
Red Hat Product
Release
thunderbird
RHEL 9
0:140.9.0-1.el9_7
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
thunderbird
Amazon Linux 2
0:140.9.0-1.amzn2.0.2
fixed