CVE-2006-5445 in Asterisk
Summary
by MITRE
Unspecified vulnerability in the SIP channel driver (channels/chan_sip.c) in Asterisk 1.2.x before 1.2.13 and 1.4.x before 1.4.0-beta3 allows remote attackers to cause a denial of service (resource consumption) via unspecified vectors that result in the creation of "a real pvt structure" that uses more resources than necessary.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2006-5445 affects the SIP channel driver component within Asterisk telecommunications software versions 1.2.x prior to 1.2.13 and 1.4.x prior to 1.4.0-beta3. This issue resides within the channels/chan_sip.c file which handles Session Initiation Protocol operations for voice over IP communications. The vulnerability represents a resource consumption flaw that can be exploited remotely by attackers to cause denial of service conditions within the affected systems.
The technical flaw manifests when the SIP channel driver creates "a real pvt structure" that consumes more system resources than necessary. This occurs during the processing of SIP messages where the system allocates memory structures to handle channel operations but fails to properly manage resource allocation. The improper resource management creates a condition where each malicious SIP message or sequence can trigger the creation of excessive memory structures that persist in the system, leading to gradual resource exhaustion. This behavior aligns with CWE-400, which categorizes resource exhaustion vulnerabilities as those that allow attackers to consume system resources beyond normal operational limits.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect the entire telephony infrastructure relying on affected Asterisk versions. When exploited, the vulnerability causes the system to consume increasing amounts of memory and processing resources until the service becomes unresponsive or crashes entirely. This makes it particularly dangerous in production environments where Asterisk serves as a core communication platform for businesses, call centers, or telecommunications providers. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring authentication or local access privileges.
The vulnerability demonstrates characteristics consistent with the attack pattern described in the MITRE ATT&CK framework under the T1499 category for Network Denial of Service, where attackers specifically target network resources to prevent legitimate users from accessing services. The exploitation vector typically involves sending specially crafted SIP messages that trigger the problematic code path in the channel driver. Organizations running affected versions of Asterisk face significant risk of service interruption and potential financial impact due to communication outages. The vulnerability also represents a potential stepping stone for more sophisticated attacks as initial denial of service conditions can be used to create opportunities for further exploitation.
Mitigation strategies should focus on immediate patching of affected systems to versions 1.2.13 or 1.4.0-beta3 and later, which contain fixes for the resource management issues in the SIP channel driver. Network administrators should implement rate limiting and connection monitoring to detect unusual patterns of SIP traffic that may indicate exploitation attempts. Additionally, regular security assessments of telephony infrastructure should be conducted to identify and remediate similar vulnerabilities in other components of the communication stack. The fix implemented in the patched versions addresses the root cause by properly managing the lifecycle of pvt structures and ensuring that resource allocation matches the actual requirements of legitimate SIP operations.