Insecure Deserialization in WatchGuard Fireware OS
CVE-2026-4266

8.4HIGH

Key Information:

Vendor

Watchguard

Status
Fireware Os
Vendor
CVE Published:
30 March 2026

Badges

👾 Exploit Exists

What is CVE-2026-4266?

An Insecure Deserialization vulnerability exists in WatchGuard Fireware OS, allowing attackers with write access to the local filesystem to execute arbitrary code within the context of the portald user. This security issue affects multiple versions of Fireware OS, specifically ranging from 12.1 to 12.11.8 and 2025.1 to 2026.1.2. It is important to note that Firebox platforms without Access Portal feature support, such as the T-15 and T-35, are not impacted.

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Affected Version(s)

Fireware OS 12.1 <= 12.11.8

Fireware OS 2025.1 <= 2026.1.2

References

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

CVSS V4

Score:
8.4
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

btaol
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