A critical out-of-bounds write vulnerability, tracked as CVE-2025-9242, has been discovered in WatchGuard Fireware OS, affecting versions 11.10.2 through 11.12.4_Update1, 12.0 through 12.11.3, and 2025.1. This flaw allows remote, unauthenticated attackers to execute arbitrary code on vulnerable Firebox firewall devices by exploiting a missing length check during the IKE handshake process. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog following evidence of active exploitation, and has mandated that Federal Civilian Executive Branch (FCEB) agencies apply patches by December 3, 2025. As of mid-November, over 54,000 Firebox devices remain exposed globally, with the highest concentrations in the U.S., Italy, the U.K., Germany, and Canada.
WatchGuard released patches for the vulnerability on September 17, 2025, but only confirmed active exploitation in late October. CISA has emphasized the significant risk posed by this flaw, urging all organizations—not just federal agencies—to prioritize patching due to the attractiveness of firewall devices as targets for threat actors. The vulnerability's exploitation path allows attackers to bypass authentication, as the vulnerable code is executed before certificate validation. Organizations unable to apply mitigations are advised to discontinue use of affected products to prevent compromise.

Mallory correlates global threat intelligence with your attack surface — know if you’re exposed before adversaries strike.
4 events from the most recent confirmed update back to the earliest known activity.
Reporting on the vulnerability noted that over 54,300 WatchGuard Firebox devices worldwide were still vulnerable, with the largest concentration in the United States. The scale and methods of exploitation were not yet publicly clear.
CISA added WatchGuard Fireware OS vulnerability CVE-2025-9242 to its Known Exploited Vulnerabilities catalog after evidence showed it was being actively exploited in attacks. Federal Civilian Executive Branch agencies were directed to remediate the issue by December 3, 2025.
WatchGuard released security updates to fix CVE-2025-9242 in Fireware OS. The flaw was considered highly critical because it could be exploited pre-authentication on exposed Firebox devices.
watchTowr Labs disclosed CVE-2025-9242, a critical out-of-bounds write in the iked process of WatchGuard Fireware OS. The bug stems from a missing length check during the IKE handshake and allows remote unauthenticated code execution before login.
Vulnerabilities, threat actors, malware, products, organizations, and breaches Mallory has linked to this story.
3 references tracked. Mallory keeps watching after this page renders.
thehackernews.com
Open sourcebleepingcomputer.com
Open sourcescworld.com
Open sourceMap indicators from this story to your assets and identify affected systems in minutes.
Every observed campaign, victim, and pivot linked to actors named in this story.
Malware, exploits, and IOCs connected to the activity described here.
YARA, Sigma, and Snort rules deployed to your SIEM as soon as they’re published.
Get matching new stories delivered to your team as they break — not the next morning.
Ask questions about this story and take action on the answers.