CVE-2009-2050 in Unified Communications Manager
Summary
by MITRE
Cisco Unified Communications Manager (aka CUCM, formerly CallManager) before 6.1(1) allows remote attackers to cause a denial of service (voice-services outage) via a malformed header in a SIP message, aka Bug ID CSCsi46466.
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Analysis
by VulDB Data Team • 02/03/2025
Cisco Unified Communications Manager versions prior to 6.1(1) contain a critical vulnerability that enables remote attackers to trigger a denial of service condition through the manipulation of SIP message headers. This vulnerability specifically targets the SIP message processing functionality within the unified communications platform, where the system fails to properly validate incoming SIP headers. The flaw manifests when the system receives a malformed header in a SIP message, causing the voice services to become unavailable and disrupting communication for all users relying on the affected system.
The technical root cause of this vulnerability resides in insufficient input validation mechanisms within the SIP processing module of Cisco Unified Communications Manager. When the system encounters a malformed header during SIP message parsing, the application does not properly handle the error condition, leading to an uncontrolled crash or restart of the voice services component. This behavior aligns with CWE-129, which addresses issues related to insufficient validation of input boundaries, and CWE-248, which covers the exposure of an exception or error condition. The vulnerability specifically affects the SIP protocol implementation within the CUCM system, where the message parsing logic does not adequately sanitize header values before processing them.
The operational impact of this vulnerability extends beyond simple service disruption, as it can result in complete voice service outages affecting enterprise communications infrastructure. Organizations relying on Cisco Unified Communications Manager for their business-critical voice communications face significant operational risks when this vulnerability exists in their environment. The remote nature of the attack means that threat actors can exploit this weakness from outside the network perimeter without requiring authentication or physical access to the system. This vulnerability directly impacts the availability aspect of the CIA triad and can be categorized under ATT&CK technique T1499.004, which describes network denial of service attacks targeting communications systems.
Mitigation strategies for this vulnerability include applying the official Cisco security patches and updates released for Cisco Unified Communications Manager version 6.1(1) and subsequent releases. Organizations should also implement network-based controls such as SIP message filtering and header validation at network boundaries to prevent malformed SIP traffic from reaching the affected systems. Network segmentation and access control measures can help reduce the attack surface, while monitoring systems should be deployed to detect unusual SIP traffic patterns that may indicate exploitation attempts. Regular security assessments and vulnerability scanning of unified communications infrastructure should be conducted to identify similar weaknesses in other components of the communications ecosystem.