CVE-2007-0481 in IOS
Summary
by MITRE
Cisco IOS allows remote attackers to cause a denial of service (crash) via a crafted IPv6 Type 0 Routing header.
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Analysis
by VulDB Data Team • 06/14/2025
The vulnerability identified as CVE-2007-0481 represents a critical denial of service flaw within Cisco IOS operating systems that affects network infrastructure devices. This vulnerability specifically targets the handling of IPv6 packets containing crafted Type 0 Routing headers, which are part of the IPv6 routing header specification defined in RFC 2460. The flaw exists in how Cisco IOS processes these particular routing headers, creating a condition where specially crafted packets can trigger unexpected behavior in the network device's packet processing engine.
The technical implementation of this vulnerability stems from inadequate input validation within the IPv6 processing module of Cisco IOS. When a device receives an IPv6 packet with a Type 0 Routing header that contains malformed or unexpected data, the IOS kernel fails to properly handle the packet structure, leading to a system crash or complete device reboot. This occurs because the routing header processing code does not adequately validate the header length field or the contents of the header itself, allowing malicious actors to craft packets that exploit buffer overflows or other memory corruption conditions. The vulnerability manifests when the device attempts to parse the malformed header and process it through the IPv6 routing mechanisms, ultimately causing the operating system to enter an unrecoverable state.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network infrastructures. Network administrators face significant risks when devices running affected Cisco IOS versions are exposed to untrusted network traffic, as a single malicious packet can bring down critical network equipment such as routers, firewalls, or switches. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, making it particularly dangerous for devices with public network interfaces or those serving as internet gateways. In enterprise environments, this could result in widespread network outages, service interruptions, and potential data loss during the recovery process. The vulnerability affects a broad range of Cisco IOS products including various router and switch platforms, making it a widespread concern across network infrastructure deployments.
Mitigation strategies for CVE-2007-0481 should focus on both immediate defensive measures and long-term architectural improvements. Network administrators should implement access control lists and packet filtering rules to block IPv6 packets containing Type 0 Routing headers, particularly on interfaces that do not require IPv6 routing functionality. Cisco released specific software patches and IOS updates that address the vulnerability by strengthening input validation and adding proper bounds checking for IPv6 routing headers. Organizations should also consider implementing network segmentation to isolate critical infrastructure from potentially malicious traffic sources and deploy intrusion detection systems that can identify and alert on suspicious IPv6 packet patterns. The vulnerability aligns with CWE-129 Input Validation and CWE-125 Out-of-bounds Read categories, and represents a technique that adversaries might leverage through the ATT&CK framework under the Network Denial of Service tactic, potentially progressing to the broader Impact category where system availability is compromised. Regular vulnerability assessments and network monitoring should be conducted to ensure that all affected devices have been properly patched and that no residual vulnerabilities remain in the network infrastructure.