CVE-2014-2129 in ASA
Summary
by MITRE
The SIP inspection engine in Cisco Adaptive Security Appliance (ASA) Software 8.2 before 8.2(5.48), 8.4 before 8.4(6.5), 9.0 before 9.0(3.1), and 9.1 before 9.1(2.5) allows remote attackers to cause a denial of service (memory consumption or device reload) via crafted SIP packets, aka Bug ID CSCuh44052.
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Analysis
by VulDB Data Team • 05/10/2026
The vulnerability described in CVE-2014-2129 represents a critical flaw in the Session Initiation Protocol inspection engine of Cisco Adaptive Security Appliance software versions prior to specific patch releases. This vulnerability affects multiple major versions including 8.2.x series before 8.2(5.48), 8.4.x series before 8.4(6.5), 9.0.x series before 9.0(3.1), and 9.1.x series before 9.1(2.5). The flaw resides in how the ASA software processes incoming SIP packets, specifically within its inspection mechanisms designed to monitor and control SIP traffic flows.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the SIP inspection engine. When the ASA device receives specially crafted SIP packets that exploit malformed or unexpected packet structures, the inspection engine fails to properly handle these malformed inputs. This leads to excessive memory consumption or triggers a device reload, effectively causing a denial of service condition that disrupts legitimate network traffic and service availability. The vulnerability operates at the protocol inspection layer, where the device should be filtering and monitoring SIP communications but instead becomes vulnerable to malformed packet processing that exhausts system resources or causes system instability.
From an operational impact perspective, this vulnerability presents a significant risk to network availability and business continuity for organizations relying on Cisco ASA appliances for network security. The remote exploitation capability means attackers can potentially disrupt services without requiring physical access or local network privileges, making the attack surface particularly concerning for enterprise networks. The denial of service can manifest as either gradual memory exhaustion that leads to system instability or immediate device reloads that completely interrupt network services. This vulnerability directly impacts the availability aspect of the CIA triad and can affect VoIP services, unified communications, and other SIP-based applications that depend on the ASA for security filtering and traffic control.
Organizations affected by this vulnerability should prioritize immediate patching of their Cisco ASA appliances to versions that contain the necessary security fixes. The mitigation strategy involves updating to the patched software versions mentioned in the advisory, specifically targeting the release numbers that address the memory handling and input validation issues within the SIP inspection engine. Network administrators should also consider implementing additional monitoring and alerting mechanisms to detect unusual memory consumption patterns or device reload events that might indicate exploitation attempts. From a cybersecurity framework perspective, this vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and relates to ATT&CK technique T1499.002 for network denial of service attacks. Organizations should also implement network segmentation and access controls to limit potential attack vectors while applying the necessary software patches to address the root cause of the vulnerability.
The vulnerability demonstrates the importance of proper input validation and resource management in network security appliances, particularly those handling protocol inspection functions. It highlights the need for comprehensive testing and validation of security device software, especially when processing complex protocols like SIP that involve multiple message types and stateful operations. Security teams should also consider implementing intrusion detection systems that can identify and alert on suspicious SIP traffic patterns that might indicate exploitation attempts, providing additional defense-in-depth measures beyond the software patches.