What’s Vulnerable › Vulnerabilities

CVE-2025-6999: WatchGuard Firebox Authentication Portal Request Smuggling Vulnerability

• Severity: medium (CVSS 6.9 v4.0)
• 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: 2025-09-15 · updated 2026-08-10
• Weakness: CWE-444

Description

An HTTP Request Smuggling [CWE-444] vulnerability in the Authentication portal of WatchGuard Fireware OS allows a remote attacker to evade request parameter sanitation and perform a reflected self-Cross-Site Scripting (XSS) attack. WatchGuard does not believe there is a practical exploit chain with a meaningful security impact for this vulnerability.

Affected products

• WatchGuard Fireware OS: from 12.0 before 12.11.3 — fixed in 12.11.3

How to fix

Upgrade to a fixed version: WatchGuard Fireware OS 12.11.3. Check the vendor advisory for mitigations.

References

• https://psirt.watchguard.com/CVE-2025-6999
• https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2025-00014

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