CVE-2026-4266

WatchGuard Firebox Insecure Deserialization in Fireware Access Portal

Published Mar 30, 2026 CVSS 4.0 · 8.4 High EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

Fireware OS 2026.2, Fireware OS 12.12, Fireware OS 12.11.9

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Watchguard firebox Cloud
Watchguard firebox M270
Watchguard firebox M290
Watchguard firebox M295
Watchguard firebox M370
Watchguard firebox M390
Watchguard firebox M395
Watchguard firebox M440
Watchguard firebox M4600
Watchguard firebox M470
Watchguard firebox M4800
Watchguard firebox M495
Watchguard firebox M5600
Watchguard firebox M570
Watchguard firebox M5800
Watchguard firebox M590
Watchguard firebox M595
Watchguard firebox M670
Watchguard firebox M690
Watchguard firebox M695
Watchguard firebox Nv5
Watchguard firebox T115-w
Watchguard firebox T125
Watchguard firebox T125-w
Watchguard firebox T145
Watchguard firebox T145-w
Watchguard firebox T185
Watchguard firebox T20
Watchguard firebox T25
Watchguard firebox T40
Watchguard firebox T45
Watchguard firebox T55
Watchguard firebox T70
Watchguard firebox T80
Watchguard firebox T85
Watchguard fireboxv
Watchguard fireware
CPEs cpe:2.3:a:watchguard:firebox_cloud:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m270:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m290:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m295:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m370:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m390:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m395:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m440:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m4600:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m470:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m4800:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m495:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m5600:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m570:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m5800:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m590:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m595:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m670:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m690:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_m695:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_nv5:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t115-w:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t125-w:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t125:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t145-w:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t145:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t185:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t20:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t25:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t40:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t45:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t55:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t70:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t80:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:firebox_t85:-:*:*:*:*:*:*:*
cpe:2.3:h:watchguard:fireboxv:-:*:*:*:*:*:*:*
cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:*
Vendors & Products Watchguard firebox Cloud
Watchguard firebox M270
Watchguard firebox M290
Watchguard firebox M295
Watchguard firebox M370
Watchguard firebox M390
Watchguard firebox M395
Watchguard firebox M440
Watchguard firebox M4600
Watchguard firebox M470
Watchguard firebox M4800
Watchguard firebox M495
Watchguard firebox M5600
Watchguard firebox M570
Watchguard firebox M5800
Watchguard firebox M590
Watchguard firebox M595
Watchguard firebox M670
Watchguard firebox M690
Watchguard firebox M695
Watchguard firebox Nv5
Watchguard firebox T115-w
Watchguard firebox T125
Watchguard firebox T125-w
Watchguard firebox T145
Watchguard firebox T145-w
Watchguard firebox T185
Watchguard firebox T20
Watchguard firebox T25
Watchguard firebox T40
Watchguard firebox T45
Watchguard firebox T55
Watchguard firebox T70
Watchguard firebox T80
Watchguard firebox T85
Watchguard fireboxv
Watchguard fireware
Metrics cvssV3_1

{'score': 6.7, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
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. 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.
CPEs cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:12.1
cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:2025.1
cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:*
References
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title WatchGuard Firebox Insecure Deserialization in Fireware Access Portal
First Time appeared Watchguard
Watchguard fireware Os
Weaknesses CWE-502
CPEs cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:12.1
cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:2025.1
Vendors & Products Watchguard
Watchguard fireware Os
References
Metrics cvssV4_0

{'score': 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'}