CVE-2026-84637

EUVD-2026-69703
Malicious calendar invitations could use file URI attachments to launch local or network-hosted executables on Windows, bypassing Thunderbird's normal executable attachment protections. With the new invitation display enabled, the attachment could also appear under a misleading filename. This vulnerability was fixed in Thunderbird 154 and Thunderbird 153.2.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mozillaCNA
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 48.87%
Affected Products (NVD)
VendorProductVersion
mozillathunderbird
𝑥
< 153.2.0
mozillathunderbird
154.0 ≤
𝑥
< 155.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mozillathunderbird
𝑥
< 154
CNA
mozillathunderbird_esr
141.0.0 ≤
𝑥
< 153.2.0
CNA
Debian logo
Debian Releases
Debian Product
Codename
thunderbird
bookworm
1:140.12.0esr-1~deb12u1
fixed
bookworm (security)
1:140.17.0esr-1~deb12u1
fixed
forky
1:153.4.0esr-1
fixed
sid
1:153.4.0esr-1
fixed
trixie
1:140.12.0esr-1~deb13u1
fixed
trixie (security)
1:140.17.0esr-1~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
thunderbird
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
MozillaThunderbird
suse enterprise desktop 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise workstation 15 SP7
153.2.0-150400.13.3.1
fixed
MozillaThunderbird-translations-common
suse enterprise desktop 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise workstation 15 SP7
153.2.0-150400.13.3.1
fixed
MozillaThunderbird-translations-other
suse enterprise desktop 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise sap 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise server 15 SP7
153.2.0-150400.13.3.1
fixed
suse enterprise workstation 15 SP7
153.2.0-150400.13.3.1
fixed
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/show_bug.cgi?id=2043878
https://www.mozilla.org/security/advisories/mfsa2026-78/
https://www.mozilla.org/security/advisories/mfsa2026-88/