CVE-2010-0591 in Unified Communications Manager
Summary
by MITRE
Cisco Unified Communications Manager (aka CUCM, formerly CallManager) 6.x before 6.1(5), 7.x before 7.1(3b)SU2, and 8.x before 8.0(1) allows remote attackers to cause a denial of service (process failure) via a malformed SIP REG message, related to an overflow of the Telephone-URL field, aka Bug ID CSCtc62362.
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Analysis
by VulDB Data Team • 05/01/2026
Cisco Unified Communications Manager versions 6.x before 6.1(5), 7.x before 7.1(3b)SU2, and 8.x before 8.0(1) contain a vulnerability in their Session Initiation Protocol implementation that enables remote attackers to trigger process failures through specifically crafted SIP REG messages. This vulnerability stems from insufficient input validation within the Telephone-URL field processing mechanism, where malformed data can cause buffer overflows that ultimately result in service disruption. The flaw exists in the SIP registration handling code path where the system fails to properly sanitize or limit the length of the telephone-URL field in incoming SIP registration requests. This vulnerability maps to CWE-121 Stack-based Buffer Overflow, as the malformed input causes the system to write beyond the allocated buffer space in memory, leading to process termination and denial of service conditions.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the core communication infrastructure of organizations relying on Cisco Unified Communications Manager for voice and video services. When exploited, the vulnerability allows attackers to remotely initiate denial of service conditions that can render the entire communication system inoperable, affecting business continuity and potentially disrupting critical operations. The attack requires minimal privileges as it can be executed remotely without authentication, making it particularly dangerous for organizations that depend on continuous communication services. The vulnerability demonstrates a classic weakness in input validation and memory management practices that aligns with ATT&CK technique T1499.004 for network denial of service attacks.
Organizations affected by this vulnerability should immediately implement mitigation strategies including applying the relevant Cisco security patches and updates, configuring SIP registration rate limiting to prevent flooding attacks, and implementing network segmentation to limit exposure. The Cisco Security Advisory provides specific patch versions for each affected release, with 6.1(5), 7.1(3b)SU2, and 8.0(1) serving as minimum recommended versions. Network administrators should also consider implementing intrusion detection systems that can identify and block malformed SIP traffic patterns, while monitoring for unusual registration request volumes that may indicate exploitation attempts. Additionally, organizations should conduct thorough testing of patch deployments in non-production environments to ensure compatibility with existing telephony infrastructure and avoid unintended service disruptions during the remediation process.