CVE-2026-4266

published 2026-03-30

CVE-2026-4266: An Insecure Deserialization vulnerability in WatchGuard Fireware OS allows an attacker that has obtained write access to the local filesystem through another…

Priority P3 37 medium 6.7 CVSS 3.1

AV L AC L PR H UI N S U C H I H A H

An Insecure Deserialization vulnerability in WatchGuard Fireware OS allows an attacker that has obtained write access to the local filesystem through another vulnerability to execute arbitrary code in the context of the portald user.

Note, this vulnerability does not affect Firebox platforms that do not support the Access Portal feature, including the T15 and T35.

Affected

5 ranges

Vendor	Product	Version range	Fixed in
watchguard	fireware	>= 12.1 < 12.12	12.12
watchguard	fireware	>= 2025.1 < 2026.2	2026.2
watchguard	fireware_os	>= 12.1 < 12.12	12.12
watchguard	fireware_os	>= 12.1 < 12.11.9	12.11.9
watchguard	fireware_os	>= 2025.1 < 2026.2	2026.2

CVSS provenance

nvd v3.1 6.7 MEDIUM CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

nvd v4.0 8.4 HIGH CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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