CVE-2026-19316 in Fireware
Summary
by MITRE • 08/28/2026
A double-free vulnerability in the WatchGuard Fireware OS iked process allows a remote unauthenticated attacker to create a Denial of Service (DoS) condition in VPN processing by sending specially crafted network traffic.
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Analysis
by VulDB Data Team • 08/28/2026
The identified security flaw resides within the Internet Key Exchange daemon, commonly referred to as iked, which is a critical component of the WatchGuard Fireware operating system responsible for managing IPsec tunnel negotiations and key exchanges. This specific vulnerability manifests as a double-free error, a memory corruption issue where the software attempts to deallocate a block of memory that has already been freed by a previous operation. In the context of network security appliances handling VPN connections, such an error typically occurs during the processing of malformed or specially crafted IKE packets sent by an unauthenticated remote attacker. The iked process does not adequately validate the state of memory pointers before attempting to release them again, leading to undefined behavior within the application's runtime environment.
From a technical perspective, double-free vulnerabilities are particularly dangerous because they can lead to heap corruption, which may be exploited for arbitrary code execution in many scenarios. However, in this specific instance involving the WatchGuard Fireware OS iked process, the primary observed impact is a Denial of Service condition rather than remote code execution. When the daemon encounters the double-free error while processing maliciously crafted network traffic, it triggers an abnormal termination or crash of the IKE service. Since the iked process is essential for establishing and maintaining IPsec VPN tunnels, its failure disrupts all active VPN connections managed by that instance. This results in a loss of connectivity for users relying on secure remote access through the firewall, effectively creating a localized denial of service against VPN services without requiring any prior authentication or valid credentials from the attacker.
The operational impact of this vulnerability is significant for organizations utilizing WatchGuard firewalls to provide secure remote access via IPsec tunnels. An unauthenticated attacker located anywhere on the internet can exploit this flaw by sending specific, malformed IKE packets designed to trigger the memory corruption bug. The successful exploitation leads to a crash in the VPN processing subsystem, causing immediate disruption of service. This means that legitimate users are unable to establish new connections or maintain existing ones until the iked process is restarted or the firewall device itself is rebooted. For high-availability environments where continuous connectivity is critical, this vulnerability poses a substantial risk to business continuity and operational stability. The lack of authentication requirements for exploitation makes it particularly attractive to automated scanning tools and opportunistic attackers seeking to disrupt network infrastructure without needing prior access credentials.
Mitigation strategies should focus on both immediate remediation and long-term security hardening. WatchGuard has likely released firmware updates that patch this memory management flaw by implementing proper checks before freeing memory pointers, ensuring that each block is only deallocated once. Administrators must apply the latest available patches to their Fireware OS installations immediately upon release. In addition to software updates, network-level mitigations can help reduce exposure. Implementing strict ingress filtering and rate limiting on UDP ports used for IKE traffic, typically port 500 and 4500, can help mitigate the volume of malicious packets reaching the iked process. Furthermore, deploying intrusion prevention systems with signatures capable of detecting malformed IKE packet structures can provide an additional layer of defense by dropping suspicious traffic before it reaches the vulnerable application logic.
This vulnerability aligns with CWE-415, which defines double free as a condition where memory is freed more than once, potentially leading to heap corruption and arbitrary code execution or denial of service. From an offensive security perspective, this exploit technique falls under MITRE ATT&CK techniques related to resource exhaustion, specifically T1499 Endpoint Denial of Service or T1529 System Shutdown/Reboot if the crash leads to a full system halt rather than just process restart. Understanding these classifications helps in mapping the vulnerability to broader threat models and ensuring that defensive controls are aligned with industry-standard frameworks for detecting and preventing such memory corruption attacks. Continuous monitoring of firewall logs for unexpected iked crashes or service interruptions can also aid in early detection of exploitation attempts, allowing security teams to respond swiftly before widespread disruption occurs.