What’s Vulnerable › Vulnerabilities

CVE-2026-86134: Fireware OS Pre-Authentication NULL Pointer Dereference Allows Remote Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-30 · updated 2026-10-06
• Weakness: CWE-476

Description

A NULL pointer dereference vulnerability in the WatchGuard Fireware OS authentication process allows a remote, unauthenticated attacker to crash the management daemon by sending a specially request to the login interface, resulting in a denial of service.

Affected products

• WatchGuard Fireware OS: from 12.0 before 12.5.21; from 12.12 before 12.12.3; from 2025.0 before 2026.2.3; from 2026.3 before 2026.3.2 — fixed in 12.12.3, 12.5.21, 2026.2.3, 2026.3.2

How to fix

Upgrade to a fixed version: WatchGuard Fireware OS 12.12.3, 12.5.21, 2026.2.3, 2026.3.2. Check the vendor advisory for mitigations.

References

• https://psirt.watchguard.com/CVE-2026-86134

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