CVE-2026-84642

EUVD-2026-69711
The values of the mail.allowed_attachment_hostnames advanced config setting were used in a regular expression without escaping. For some possible valid hostnames, this could allow certain unintended hostnames to also match and serve remote attachments. This vulnerability was fixed in Thunderbird 155 and Thunderbird 153.2.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
mozillaCNA
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 34.52%
Affected Products (NVD)
VendorProductVersion
mozillathunderbird
𝑥
< 153.2.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mozillathunderbird
154.0 ≤
𝑥
< 155.0
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