CVE-2012-5017 in ASR 1002 Router
Summary
by MITRE
Cisco IOS before 15.1(1)SY1 allows remote authenticated users to cause a denial of service (device reload) by establishing a VPN session and then sending malformed IKEv2 packets, aka Bug ID CSCub39268.
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Analysis
by VulDB Data Team • 05/11/2026
Cisco IOS versions prior to 15.1(1)SY1 contain a critical vulnerability that enables remote authenticated attackers to trigger a device reload through a carefully crafted sequence involving VPN sessions and malformed IKEv2 packets. This vulnerability specifically affects the Internet Key Exchange version 2 implementation within the IOS operating system, creating a condition where legitimate authenticated users can exploit a flaw in packet processing logic to cause unauthorized device restarts. The vulnerability operates through the IKEv2 protocol handler which fails to properly validate incoming packets during the VPN establishment phase, allowing attackers to send malformed packets that cause memory corruption and subsequent system instability.
The technical flaw resides in the IKEv2 packet parsing mechanism where the system does not adequately sanitize or validate packet structures received during the authentication and key exchange process. When an authenticated user establishes a VPN session and subsequently sends malformed IKEv2 packets, the IOS kernel encounters unexpected data structures that lead to memory allocation errors and eventually trigger a system reload. This represents a classic buffer overflow condition or improper input validation issue that falls under CWE-129, which addresses issues related to insufficient validation of length fields. The vulnerability is particularly concerning because it requires only authenticated access to exploit, meaning that an attacker with valid credentials can cause a denial of service condition that affects the availability of the network infrastructure.
The operational impact of CVE-2012-5017 extends beyond simple service disruption as it can be leveraged to create persistent availability issues that affect network operations and business continuity. Network administrators may find their devices repeatedly reloading, causing temporary loss of connectivity for users and potentially creating security gaps during the restart process. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and specifically targets the availability aspect of the CIA triad by compromising system uptime. Organizations using affected Cisco IOS versions face significant risk as the attack can be executed from within the network perimeter, making it difficult to detect and prevent through traditional network monitoring approaches.
Mitigation strategies for this vulnerability require immediate implementation of Cisco IOS software updates to version 15.1(1)SY1 or later, which contain patches addressing the IKEv2 packet validation issues. Network administrators should also implement network segmentation to limit the scope of potential exploitation and consider disabling IKEv2 functionality if it is not essential for operations. Additional defensive measures include implementing intrusion detection systems that can identify anomalous IKEv2 packet patterns and monitoring for unusual device reload events. The vulnerability demonstrates the importance of proper input validation in network protocol implementations and serves as a reminder of the critical need for regular security updates in network infrastructure devices. Organizations should also consider implementing network access controls to limit which authenticated users can establish VPN sessions and perform actions that could lead to device instability.