CVE-2026-78009 in Fireware OS
Summary
by MITRE • 08/28/2026
An out-of-bounds read 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 vulnerability 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 security associations and key exchange protocols. This specific flaw manifests as an out-of-bounds read condition, indicating that the software fails to properly validate memory access boundaries when processing incoming network packets destined for VPN establishment or maintenance. The technical root cause lies in insufficient input validation within the iked process logic, where crafted packet payloads trigger a memory read operation beyond the allocated buffer limits. This type of error typically occurs during the parsing of IKE protocol messages, particularly those involving complex payload structures or unexpected data lengths that exceed expected parameters defined by the implementation rather than just the RFC standards.
From an operational perspective, this vulnerability poses a significant risk to network availability and integrity. Because the flaw allows for remote exploitation without requiring any form of authentication, it presents a severe threat vector against organizations relying on WatchGuard firewalls for secure site-to-site or remote access VPN services. An unauthenticated attacker located anywhere on the internet can target vulnerable systems by sending specially crafted traffic designed to trigger the out-of-bounds read condition. The immediate consequence of exploiting this flaw is a Denial of Service, as the iked process may crash or become unstable upon encountering invalid memory references. This disruption halts VPN connectivity for legitimate users and potentially destabilizes the firewall appliance itself if the error propagates beyond the specific daemon context, leading to broader system instability or requiring manual intervention to restore service.
The classification of this vulnerability aligns with Common Weakness Enumeration identifier CWE-125, which describes out-of-bounds read operations that allow attackers to access sensitive memory contents or cause application crashes depending on how the operating system handles the illegal memory access. In terms of tactical behavior within a cyber kill chain, this exploitation technique corresponds to ATT&CK tactic T1498, specifically Network Denial of Service via resource exhaustion or service disruption through protocol abuse. The lack of authentication requirements places it in the initial attack phases where adversaries seek low-effort entry points that yield high impact on availability metrics rather than confidentiality or integrity at this stage.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. The primary defense is to apply the vendor-provided software update immediately, which patches the memory validation logic within the iked process to ensure strict bounds checking before any read operations are executed. Until the patch is applied, network administrators should consider implementing access control lists that restrict IKE traffic sources to only known and trusted IP addresses, thereby reducing the attack surface available to unauthenticated remote actors. Additionally, enabling deep packet inspection features if available can help identify anomalous payload structures characteristic of this exploit before they reach the vulnerable daemon logic. Regular monitoring of firewall logs for unusual spikes in IKE negotiation failures or process restarts is also recommended as an early warning mechanism for potential exploitation attempts.