Critical Out-of-Bounds Write Vulnerability in WatchGuard Fireware OS Enables Remote Code Execution (CVE-2025-9242)
A critical out-of-bounds write vulnerability (CVE-2025-9242) has been identified in WatchGuard Fireware OS, affecting VPN configurations using IKEv2. The flaw allows remote, unauthenticated attackers to execute arbitrary code. WatchGuard has released patches and advises immediate updates to mitigate risk.
Sep 17, 2025
Critical WatchGuard Fireware Vulnerability Actively Exploited
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.
Nov 13, 2025
Critical Remote Code Execution Vulnerability in WatchGuard Fireware OS VPN (CVE-2025-9242)
A critical security vulnerability, tracked as CVE-2025-9242, was discovered in WatchGuard Fireware OS, which powers WatchGuard’s Firebox network security appliances. This flaw is an out-of-bounds write vulnerability in the iked process, specifically within the function 'ike2_ProcessPayload_CERT' in the file 'src/ike/iked/v2/ike2_payload_cert.c'. The vulnerability arises due to a missing length check on the identification buffer, allowing a remote, unauthenticated attacker to trigger a stack-based buffer overflow. Exploitation of this flaw enables arbitrary code execution during the IKE_SA_AUTH phase of the IKEv2 handshake, which is used to establish VPN tunnels. The vulnerability affects both mobile user VPNs and branch office VPNs configured with dynamic gateway peers, making it a significant risk for organizations relying on these features. Fireware OS versions 11.10.2 up to and including 11.12.4_Update1, 12.0 up to and including 12.11.3, and 2025.1 are impacted, with fixes released in 2025.1.1, 12.11.4, 12.3.1_Update3 (FIPS-certified), and 12.5.13 for specific models. The 11.x branch has reached end-of-life and is no longer supported. Security researchers, including McCaulay Hudson of watchTowr Labs, highlighted that the vulnerability is particularly attractive to ransomware groups due to its remote, unauthenticated nature and the fact that it targets internet-exposed perimeter appliances. WatchGuard’s Fireware OS is widely deployed, protecting over 250,000 small and midsize enterprises and more than 10 million endpoints globally, amplifying the potential impact of this vulnerability. The flaw was disclosed and patched following responsible disclosure, with WatchGuard issuing an advisory and urging customers to update affected devices immediately. The vulnerability underscores the ongoing risk posed by classic buffer overflow issues, even in modern enterprise-grade security appliances. Researchers were able to reproduce the exploit, demonstrating the ease with which attackers could compromise vulnerable systems. The lack of mainstream exploit mitigations in the affected code path further increases the risk of successful exploitation. Organizations using WatchGuard Fireware OS are advised to review their VPN configurations, apply the latest patches, and consider additional monitoring for signs of exploitation. The incident highlights the importance of timely patch management and the persistent threat posed by memory safety vulnerabilities in critical infrastructure.
Oct 17, 2025