CVE-2012-5427 in IOS
Summary
by MITRE
Cisco IOS Unified Border Element (CUBE) in Cisco IOS before 15.3(2)T allows remote authenticated users to cause a denial of service (input queue wedge) via a crafted series of RTCP packets, aka Bug ID CSCuc42518.
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Analysis
by VulDB Data Team • 05/11/2026
The vulnerability CVE-2012-5427 affects Cisco IOS Unified Border Element (CUBE) devices running IOS versions prior to 15.3(2). This issue represents a significant denial of service weakness that can be exploited by authenticated remote attackers to disrupt network operations. The vulnerability specifically targets the input queue handling mechanism within the CUBE component, which is designed to manage signaling and media streams in unified communications environments. The affected devices operate as border elements that facilitate communication between different network domains, making them critical infrastructure components for enterprise voice and video services.
The technical flaw manifests through a crafted sequence of RTCP (Real-time Transport Control Protocol) packets that are processed by the CUBE's input queue management system. RTCP packets are normally used for monitoring transmission statistics and quality of service parameters in real-time media applications. When these packets are specially constructed and transmitted in a particular sequence, they trigger a condition where the input queue becomes wedged or blocked, preventing further processing of legitimate traffic. This behavior creates a cascading effect that can render the CUBE device unable to handle incoming media streams or signaling messages, effectively causing a denial of service condition. The vulnerability operates at the protocol processing layer where the device fails to properly validate or handle malformed packet sequences, leading to resource exhaustion or state corruption within the input queue subsystem.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the reliability of unified communications infrastructure. Organizations relying on CUBE devices for voice and video services may experience complete communication outages, particularly in environments where these devices serve as critical gateways between different network segments. The authenticated nature of the attack means that an attacker must first establish valid credentials to exploit the vulnerability, but this access level is often sufficient to compromise network services. The vulnerability affects devices deployed in enterprise networks, service provider environments, and any organization utilizing Cisco's unified border elements for managing VoIP and multimedia traffic. Security incidents involving this vulnerability typically result in extended downtime and require immediate remediation to restore normal network operations.
Mitigation strategies for CVE-2012-5427 primarily focus on applying the appropriate software patches and implementing network segmentation controls. Organizations should immediately upgrade their CUBE devices to IOS version 15.3(2)T or later, which contains the necessary code fixes to prevent the input queue wedge condition. Network administrators should also implement rate limiting and packet filtering mechanisms to reduce the impact of potentially malicious RTCP traffic. The vulnerability aligns with CWE-129, which addresses improper validation of input data, and relates to ATT&CK technique T1499.004 for network denial of service attacks. Additional defensive measures include monitoring input queue utilization patterns, implementing intrusion detection systems to identify anomalous RTCP packet sequences, and maintaining detailed network logs to track potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to ensure all CUBE devices remain protected against similar issues in the future.