CVE-2026-0891

EUVD-2026-2344
Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. 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 < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8.1 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA-ADPADP
8.1 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 6%
Affected Products (NVD)
VendorProductVersion
mozillafirefox
𝑥
< 140.7.0
mozillafirefox
𝑥
< 147.0
mozillathunderbird
𝑥
< 140.7.0
mozillathunderbird
𝑥
< 147.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
148.0-1
fixed
firefox-esr
bookworm
vulnerable
bookworm (security)
140.8.0esr-1~deb12u1
fixed
bullseye
vulnerable
bullseye (security)
140.7.0esr-1~deb11u1
fixed
forky
140.7.0esr-1
fixed
sid
140.8.0esr-1
fixed
trixie
vulnerable
trixie (security)
140.8.0esr-1~deb13u1
fixed
thunderbird
bookworm
vulnerable
bookworm (security)
1:140.7.1esr-1~deb12u1
fixed
bullseye
vulnerable
bullseye (security)
1:140.7.1esr-1~deb11u1
fixed
forky
1:140.7.1esr-1
fixed
sid
1:140.8.0esr-1
fixed
trixie
vulnerable
trixie (security)
1:140.7.1esr-1~deb13u1
fixed
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278
https://www.mozilla.org/security/advisories/mfsa2026-01/
https://www.mozilla.org/security/advisories/mfsa2026-03/
https://www.mozilla.org/security/advisories/mfsa2026-04/
https://www.mozilla.org/security/advisories/mfsa2026-05/