What’s Vulnerable › Vulnerabilities

CVE-2026-13371: WatchGuard Firebox Management Web UI Denial of Service via Unsafe Deserialization

• Severity: medium (CVSS 4.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-03 · updated 2026-10-25
• Weakness: CWE-502

Description

An authenticated administrator can trigger a denial-of-service condition in the Fireware Management Web UI by sending malformed or crafted data to the put_data endpoint, which performs unsafe deserialization of the attacker-supplied input.

Affected products

• WatchGuard Fireware OS: from 2025.1 before 2026.2.1; from 12.5 before 12.5.19; from 12.0 before 12.12.1 — fixed in 2026.2.1, 12.5.19, 12.12.1

How to fix

Upgrade to a fixed version: WatchGuard Fireware OS 2026.2.1, 12.5.19, 12.12.1. Check the vendor advisory for mitigations.

References

• https://psirt.watchguard.com/CVE-2026-13371
• https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00014

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