CVE-2026-13376
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk19th percentile - higher than 19% of all known CVEs
Summary
A Stored Cross-Site Scripting (XSS) vulnerability was found in the spamBlocker module of WatchGuard Fireware OS due to improper input neutralization during web page generation. This is an additional unmitigated attack vector for the previously disclosed CVE-2025-1071.
Risk Assessment
An attacker can inject a malicious script that executes in the browsers of administrators or users, potentially leading to session hijacking, account takeover, or theft of sensitive data.
Recommendation
Immediately upgrade WatchGuard Fireware OS to a version later than 12.12, 12.5.18, or 2026.2, depending on the release branch, following the vendor's guidance.
Other vulnerabilities in WatchGuard Fireware OS
See all- CVE-2026-86131Critical
A code injection vulnerability in WatchGuard Fireware OS's BOVPN Over TLS client configuration handling allows an attacker who controls the remote VPN server to execute arbitrary commands as root on the connecting Firebox.
- CVE-2026-19318Critical
A stack-based buffer overflow in the iked process of WatchGuard Fireware OS allows a remote unauthenticated attacker to execute arbitrary code by sending specially crafted network traffic.
- CVE-2026-19315Critical
A type confusion vulnerability in the iked process of WatchGuard Fireware OS allows a remote unauthenticated attacker to execute arbitrary code by sending specially crafted network traffic.
- CVE-2026-19313Critical
A heap overflow vulnerability in the iked process of WatchGuard Fireware OS allows a remote unauthenticated attacker to execute arbitrary code by sending specially crafted network traffic.
- CVE-2026-13086Critical
A stack-based buffer overflow in the epm (Endpoint Protection Manager) service used by the deprecated Mobile Security feature in WatchGuard Fireware OS allows an unauthenticated remote attacker to execute arbitrary code.
- CVE-2025-14733CriticalActively exploited
An Out-of-bounds Write vulnerability in the WatchGuard Fireware OS iked process may allow a remote unauthenticated attacker to execute arbitrary code. It affects both mobile user VPN with IKEv2 and branch office VPN using IKEv2 when configured with a dynamic gateway peer. Even after deleting those configurations, if a branch office VPN to a static gateway peer remains, the Firebox may still be vulnerable.
- CVE-2025-9242CriticalActively exploited
Out-of-bounds write vulnerability in the iked process of WatchGuard Fireware OS. A remote unauthenticated attacker can execute arbitrary code. Affects mobile user VPN with IKEv2 and branch office VPN using IKEv2 when configured with a dynamic gateway peer. If configurations were deleted but a branch office VPN to a static peer remains, the device may still be vulnerable.
- CVE-2022-26318CriticalActively exploited
On WatchGuard Firebox and XTM appliances, an unauthenticated user can execute arbitrary code, aka FBX-22786. This vulnerability impacts Fireware OS before 12.7.2_U2, 12.x before 12.1.3_U8, and 12.2.x through 12.5.x before 12.5.9_U2.
- CVE-2026-86134High
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.
- CVE-2026-86133High
An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker who has completed the initial IKEv2 handshake to crash the iked process by sending a specially crafted encrypted IKEv2 message, resulting in a denial of service.
Original NVD description (English source)
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS spamBlocker module allows Stored XSS. This vulnerability is an additional unmitigated attack path for CVE-2025-1071. This issue affects Fireware OS 12.0 up to and including 12.12, 12.5 up to and including 12.5.18, and 2025.1 up to and including 2026.2.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS