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 products
watchguard: fireware; watchguard: firebox m295; watchguard: firebox m395; watchguard: firebox m495; watchguard: firebox m595; watchguard: firebox m695; watchguard: firebox t115-w; watchguard: firebox t125; watchguard: firebox t125-w; watchguard: firebox t145; watchguard: firebox t145-w; watchguard: firebox t185; watchguard: firebox cloud; watchguard: firebox m270; watchguard: firebox m290
References2
- www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00007 Vendor Advisory
- psirt.watchguard.com/CVE-2026-4266 Broken Link
Metrics
- CVSS 3.1
-
6.7
MEDIUM
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H - CVSS 4.0
-
8.4
HIGH
Score source: CNA
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 - EPSS — exploit probability
- 0% percentile: 20 · as of 12 November 2026
- CWE
- CWE-502
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.