CVE-2014-2143 in IOS
Summary
by MITRE
The IKE implementation in Cisco IOS 15.4(1)T and earlier and IOS XE allows remote attackers to cause a denial of service (security-association drop) via crafted Main Mode packets, aka Bug ID CSCun31021.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/09/2026
The vulnerability identified as CVE-2014-2143 represents a critical flaw in the Internet Key Exchange protocol implementation within Cisco IOS and IOS XE operating systems. This weakness specifically affects versions 15.4(1)T and earlier, where the IKE daemon fails to properly validate incoming Main Mode packets. The vulnerability manifests as a denial of service condition that results in the dropping of security associations, effectively disrupting secure communications between network devices. The flaw is particularly concerning because it allows remote attackers to exploit this weakness without requiring authentication, making it accessible to anyone capable of sending crafted packets to the affected system.
The technical implementation of this vulnerability stems from insufficient input validation within the IKE Main Mode processing logic. When the affected Cisco IOS or IOS XE devices receive specially crafted Main Mode packets, the IKE daemon becomes unable to properly handle the malformed data structures, leading to an abrupt termination of security association processes. This behavior creates a cascading effect where legitimate security associations are dropped, forcing network devices to renegotiate connections and potentially leaving the network vulnerable during the re-establishment period. The vulnerability operates at the network protocol level, specifically targeting the IKEv1 protocol implementation that is fundamental to establishing secure communications through IPSec tunnels.
From an operational standpoint, the impact of CVE-2014-2143 extends beyond simple service disruption to potentially compromise network security infrastructure. When security associations are dropped, it affects the integrity of IPSec connections that many enterprise networks rely upon for secure communication between branch offices, remote workers, and cloud services. The attack can be executed from any remote location with network access to the vulnerable device, making it particularly dangerous in environments where security associations are critical for maintaining secure network boundaries. Network administrators may experience intermittent connectivity issues, failed tunnel establishment, and potential security gaps that could be exploited by more sophisticated attackers.
The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how protocol implementation flaws can create denial of service conditions. From an adversarial perspective, this weakness maps to ATT&CK technique T1499.002, which involves network disruption through denial of service attacks, and T1071.004, which covers application layer protocol usage for command and control communications. Organizations should implement immediate mitigations including applying the relevant Cisco security patches, configuring access control lists to filter suspicious IKE packets, and monitoring network traffic for signs of exploitation attempts. Additionally, network segmentation strategies can help limit the potential impact of successful attacks by isolating vulnerable devices from critical network infrastructure and implementing redundant security associations to maintain availability during potential exploitation events.