The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has confirmed that ransomware gangs are also exploiting a critical WatchGuard Firebox firewall vulnerability, which it flagged as actively exploited in December.
This flaw is tracked as CVE-2025-14733 and stems from an out-of-bounds write allowing unauthenticated threat actors to execute malicious code remotely in low-complexity attacks.
This vulnerability affects firewalls running Fireware OS 11.x and later (including 11.12.4_Update1), 12.x or later (including 12.11.5), and 2025.1 through 2025.1.3.
When it released CVE-2025-14733 security patches in December, WatchGuard said unpatched Firebox firewalls are vulnerable to attacks only if configured to use IKEv2 VPN, but noted they might still be compromised even if the vulnerable configurations have been deleted if a branch office VPN to a static gateway peer is still configured.
WatchGuard also confirmed that attackers were exploiting the flaw in the wild and shared indicators of compromise to help customers check whether their Firebox devices have been hacked.
Internet security watchdog group Shadowserver found over 115,00 unpatched Firebox firewalls exposed online in December, and nearly 9,000 instances remain unsecured after nine months.
In a Thursday update to its catalog of actively exploited vulnerabilities, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) said the CVE-2025-14733 flaw is now known to be used by ransomware gangs but has not provided more details about their attacks.
CISA first added the flaw to its Known Exploited Vulnerabilities (KEV) catalog in December, when it ordered U.S. federal agencies to secure their systems within a week, as mandated by Binding Operational Directive (BOD) 22-01.
Two years ago, the cybersecurity agency ordered government agencies to patch another actively exploited WatchGuard flaw (CVE-2022-23176) affecting Firebox and XTM firewalls.
More recently, in September 2025, WatchGuard patched an RCE vulnerability (CVE-2025-9242) affecting Firebox firewalls and almost identical to CVE-2025-14733. One month later, CISA tagged the flaw as actively exploited, and Shadowserver found more than 75,000 Firebox firewalls vulnerable to attacks.
WatchGuard provides services to more than 250,000 small and mid-sized companies through a network of more than 17,000 security resellers and service providers worldwide.
Overall prevention scores can hide what happens after initial access. Once attackers are using valid credentials, prevention drops sharply.
The Blue Report 2026 measures defenses technique by technique across 338 million simulations run in customer production environments.
