CVE-2026-4266 PUBLISHED

WatchGuard Firebox Insecure Deserialization in Fireware Access Portal

Assigner: WatchGuard
Reserved: 16.03.2026 Published: 30.03.2026 Updated: 30.03.2026

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.

Metrics

CVSS 4.0

CVSS 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
CVSS Score: 8.4

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	High
User Interaction	None

CVSS 4.0

Product Status

Vendor	WatchGuard
Product	Fireware OS
Versions	Default: unaffected affected from 12.1 to 12.11.8 (incl.) affected from 2025.1 to 2026.1.2 (incl.)

Exploits

WatchGuard is not aware of any exploitation of this issue in the wild.

Credits

btaol finder

References

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

Problem Types

CWE-502 Deserialization of Untrusted Data CWE

Impacts

CAPEC-253 Remote Code Inclusion