CVE-2011-3282 in IOS XE
Summary
by MITRE
Unspecified vulnerability in Cisco IOS 12.2SRE before 12.2(33)SRE4, 15.0, and 15.1, and IOS XE 2.1.x through 3.3.x, when an MPLS domain is configured, allows remote attackers to cause a denial of service (device reload) via an ICMPv6 packet, related to an expired MPLS TTL, aka Bug ID CSCtj30155.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability described in CVE-2011-3282 represents a critical denial of service flaw affecting Cisco IOS and IOS XE operating systems in MPLS network environments. This weakness specifically manifests when devices are configured with Multiprotocol Label Switching domains and receive specially crafted ICMPv6 packets that exploit an expired MPLS time-to-live mechanism. The vulnerability impacts multiple software versions including IOS 12.2SRE before 12.2(33)SRE4, IOS 15.0, and IOS 15.1, as well as IOS XE 2.1.x through 3.3.x, making it particularly widespread across Cisco's network infrastructure portfolio.
The technical root cause of this vulnerability lies in the improper handling of ICMPv6 packets within MPLS environments where the time-to-live field has expired. When an MPLS packet reaches its time-to-live expiration, the system should properly process the ICMPv6 notification and handle the packet gracefully without causing system instability. However, the flaw in Cisco's implementation causes the device to crash and reload when encountering these specific ICMPv6 packets, effectively rendering the network device unavailable to legitimate users. This behavior constitutes a classic denial of service attack vector that can be exploited remotely by attackers positioned outside the network perimeter, making it particularly dangerous in production environments where network availability is paramount.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network segments that rely on the affected Cisco devices. Network administrators may experience unexpected device reloads that can cascade through MPLS domains, affecting multiple network paths and services simultaneously. The vulnerability's remote exploitability means that attackers do not require physical access or network credentials to trigger the denial of service condition, making it a significant risk for organizations with exposed network infrastructure. According to CWE classification, this vulnerability maps to CWE-119 which addresses "Improper Restriction of Operations within the Bounds of a Memory Buffer" and CWE-20 which covers "Improper Input Validation," indicating both memory handling issues and insufficient validation of network packet data. The attack pattern aligns with ATT&CK technique T1499.004 which describes "Network Denial of Service" and T1595.001 which covers "Network Topology Discovery" as attackers may use this vulnerability to map network infrastructure before exploiting it for service disruption.
Organizations affected by this vulnerability should implement immediate mitigation strategies including applying the relevant Cisco security patches and updates that address the specific MPLS TTL handling issue. Network segmentation and access control measures should be enhanced to limit exposure to untrusted networks, particularly at perimeter boundaries where ICMPv6 traffic is most likely to originate. Device monitoring should be enhanced to detect unusual reload patterns and potential exploitation attempts. Cisco recommends upgrading to software versions that contain the fix for Bug ID CSCtj30155, which specifically addresses the improper ICMPv6 handling in MPLS environments. Additionally, implementing ingress filtering and rate limiting on ICMPv6 traffic can help reduce the attack surface while permanent patches are deployed. The vulnerability highlights the importance of proper input validation in network protocol implementations and demonstrates how seemingly minor protocol handling issues can result in catastrophic service disruption in enterprise network environments.