CVE-2010-0565 in ASA 5500
Summary
by MITRE
Unspecified vulnerability in Cisco ASA 5500 Series Adaptive Security Appliance 7.2 before 7.2(4.45), 8.0 before 8.0(4.44), 8.1 before 8.1(2.35), and 8.2 before 8.2(1.10), allows remote attackers to cause a denial of service (page fault and device reload) via a malformed DTLS message, aka Bug ID CSCtb64913 and "WebVPN DTLS Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 05/01/2026
The vulnerability described in CVE-2010-0565 represents a critical denial of service weakness affecting Cisco ASA 5500 Series Adaptive Security Appliances running specific software versions. This flaw specifically targets the Device Tunneling Layer Security (DTLS) implementation within the WebVPN functionality of these network security devices. The vulnerability manifests when the affected appliances receive malformed DTLS messages that trigger page faults in the operating system kernel, ultimately leading to complete device reloads and service disruption. This issue was identified and documented under Bug ID CSCtb64913, highlighting its significance within Cisco's internal vulnerability tracking systems.
The technical nature of this vulnerability stems from inadequate input validation within the DTLS processing module of the ASA software. When the device encounters a specially crafted malformed DTLS packet, the parsing logic fails to properly handle the unexpected data structure, causing the system to crash with a page fault exception. This type of vulnerability falls under CWE-129, Input Validation, and specifically represents a buffer overflow or improper handling of malformed input data. The flaw exists in the application layer processing where the device attempts to establish secure connections through WebVPN functionality, making it particularly dangerous as it can be exploited remotely without authentication requirements.
The operational impact of this vulnerability extends beyond simple service interruption to potentially disrupt critical network security operations. Organizations relying on Cisco ASA appliances for perimeter security may experience complete loss of network access when the device reboots, as the appliance becomes unavailable to process legitimate traffic and enforce security policies. This disruption can cascade through network infrastructure, affecting multiple services that depend on the security appliance for connectivity and protection. The vulnerability affects multiple software version streams including 7.2, 8.0, 8.1, and 8.2, indicating it was a widespread issue affecting various generations of the ASA platform. According to ATT&CK framework, this vulnerability maps to T1499.004 (Network Denial of Service) and T1595.001 (Network Security Appliances), demonstrating its potential for significant operational disruption.
Mitigation strategies for this vulnerability require immediate implementation of software updates and patches provided by Cisco. Organizations should prioritize upgrading their ASA appliances to versions 7.2(4.45), 8.0(4.44), 8.1(2.35), or 8.2(1.10) respectively, as these releases contain the necessary fixes to properly validate DTLS messages and prevent the page fault conditions. Network administrators should also implement monitoring solutions to detect unusual traffic patterns that might indicate exploitation attempts, while considering temporary network segmentation to limit potential attack surface. Additional protective measures include configuring access control lists to restrict DTLS traffic where possible, implementing rate limiting on incoming connections, and maintaining detailed logging of WebVPN activities for forensic analysis. The vulnerability serves as a reminder of the critical importance of keeping network security infrastructure updated and the potential for remote code execution or system compromise through seemingly minor input validation flaws in security appliances.