CVE-2026-4266

Published: Mar 30, 2026Modified: Aug 28, 2026

8.4

Vector

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

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:XShow less

Source: 5d1c2695-1a31-4499-88ae-e847036fd7e3 (Secondary)

Description

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 (2)

Products: Watchguard: Fireware

Watchguard

1 product

Fireware

Configuration A

1 vulnerable · 11 platform

Vulnerable Software	Affected Versions
Watchguard Fireware	From 2025.1 to 2026.2

Running on/with	Platform Versions
Watchguard Firebox M295	All versions
Watchguard Firebox M395	All versions
Watchguard Firebox M495	All versions
Watchguard Firebox M595	All versions
Watchguard Firebox M695	All versions
Watchguard Firebox T115 W	All versions
Watchguard Firebox T125	All versions
Watchguard Firebox T125 W	All versions
Watchguard Firebox T145	All versions
Watchguard Firebox T145 W	All versions
Watchguard Firebox T185	All versions

Configuration B

1 vulnerable · 25 platform

Vulnerable Software	Affected Versions
Watchguard Fireware	From 12.1 to 12.12

Running on/with	Platform Versions
Watchguard Firebox Cloud	All versions
Watchguard Firebox M270	All versions
Watchguard Firebox M290	All versions
Watchguard Firebox M370	All versions
Watchguard Firebox M390	All versions
Watchguard Firebox M440	All versions
Watchguard Firebox M4600	All versions
Watchguard Firebox M470	All versions
Watchguard Firebox M4800	All versions
Watchguard Firebox M5600	All versions
Watchguard Firebox M570	All versions
Watchguard Firebox M5800	All versions
Watchguard Firebox M590	All versions
Watchguard Firebox M670	All versions
Watchguard Firebox M690	All versions
Watchguard Firebox Nv5	All versions
Watchguard Firebox T20	All versions
Watchguard Firebox T25	All versions
Watchguard Firebox T40	All versions
Watchguard Firebox T45	All versions
Watchguard Firebox T55	All versions
Watchguard Firebox T70	All versions
Watchguard Firebox T80	All versions
Watchguard Firebox T85	All versions
Watchguard Fireboxv	All versions

Related CWEs

CWE-502

Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

References (2)

https://psirt.watchguard.com/CVE-2026-4266

Source: 5d1c2695-1a31-4499-88ae-e847036fd7e3

Broken Link

https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00007

Source: 5d1c2695-1a31-4499-88ae-e847036fd7e3

Vendor Advisory

Timeline

No history available yet.