CVE-2026-4266

HIGH

WatchGuard Firebox Insecure Deserialization in Fireware Access Portal

Title source: cna

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.This issue affects Fireware OS: 12.1 through 12.11.8 and 2025.1 through 2026.1.2. Note, this vulnerability does not affect Firebox platforms that do not support the Access Portal feature, including the T-15 and T-35.

References (1)

[Vendor Advisory] https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00007

Scores

CVSS v4 8.4

EPSS 0.0002

EPSS Percentile 6.3%

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-502

Status published

Products (2)

WatchGuard/Fireware OS 12.1 - 12.11.8

WatchGuard/Fireware OS 2025.1 - 2026.1.2

Published Mar 30, 2026

Tracked Since Mar 30, 2026