CVE-2015-0641 in IOS XE
Summary
by MITRE
Cisco IOS XE 2.x and 3.x before 3.9.0S, 3.10 before 3.10.0S, 3.11 before 3.11.0S, 3.12 before 3.12.0S, 3.13 before 3.13.0S, 3.14 before 3.14.0S, and 3.15 before 3.15.0S allows remote attackers to cause a denial of service (device reload) via crafted IPv6 packets, aka Bug ID CSCub68073.
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Analysis
by VulDB Data Team • 04/16/2022
Cisco IOS XE software versions affected by CVE-2015-0641 represent a critical denial of service vulnerability that specifically targets the IPv6 packet processing functionality within the network operating system. This vulnerability affects multiple release branches including 2.x and 3.x series, with specific version constraints indicating that patches were released in 3.9.0S, 3.10.0S, 3.11.0S, 3.12.0S, 3.13.0S, 3.14.0S, and 3.15.0S. The flaw manifests when the system processes crafted IPv6 packets that contain malformed or specially constructed data fields, leading to a complete device reload and subsequent service disruption.
The technical implementation of this vulnerability resides in the IPv6 packet handling mechanisms of the IOS XE software stack, which operates under the Common Weakness Enumeration framework as CWE-121, representing a buffer overflow condition. When the system encounters malformed IPv6 packets, the processing logic fails to properly validate packet structures, causing memory corruption that ultimately results in a system crash and automatic device reload. This behavior aligns with the ATT&CK technique T1499.004, which describes network denial of service attacks targeting network infrastructure devices, and demonstrates how a seemingly minor packet processing flaw can escalate into a significant operational disruption.
The operational impact of CVE-2015-0641 extends beyond simple service interruption as it affects network availability and reliability across enterprise and service provider environments. Network devices running affected IOS XE versions become vulnerable to remote exploitation by attackers who can craft specific IPv6 packets to trigger the device reload, effectively creating a persistent denial of service condition. This vulnerability particularly impacts network infrastructure devices that process IPv6 traffic, including routers, switches, and firewalls that may be configured to handle IPv6 protocols. The attack vector requires only remote network access to execute, making it particularly dangerous as it can be exploited from outside the network perimeter without requiring physical access or authentication credentials.
Mitigation strategies for this vulnerability should prioritize immediate patch deployment across all affected Cisco IOS XE devices, with particular attention to network infrastructure critical to business operations. Organizations should implement network segmentation and access control measures to limit exposure to potentially malicious IPv6 traffic while monitoring for unusual packet patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining current security patches and implementing robust network monitoring solutions that can detect anomalous traffic patterns and potential exploitation attempts. Additionally, network administrators should consider implementing IPv6 traffic filtering rules that can help prevent malformed packets from reaching vulnerable systems while maintaining necessary network functionality.