CVE-2017-13006 in macOS
Summary
by MITRE
The L2TP parser in tcpdump before 4.9.2 has a buffer over-read in print-l2tp.c, several functions.
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-13006 represents a critical buffer over-read flaw within the Layer 2 Tunneling Protocol (L2TP) parser implementation of tcpdump version 4.9.2 and earlier. This issue resides in the print-l2tp.c source file and affects multiple functions within the L2TP parsing logic, making it particularly dangerous as it can be exploited through malformed network packets. The vulnerability demonstrates a classic memory safety issue where the parser fails to properly validate input data length before attempting to read from memory buffers, creating potential avenues for arbitrary code execution or system instability.
The technical flaw manifests when tcpdump processes L2TP packets that contain malformed or unexpected data structures within their headers. Specifically, the parser does not adequately check the length field of L2TP control messages or validate that sufficient data exists in the packet buffer before attempting to read beyond the intended boundaries. This condition creates a scenario where an attacker can craft malicious L2TP packets that cause the tcpdump utility to read memory locations beyond the allocated buffer space, potentially leading to information disclosure, denial of service, or in some cases, remote code execution depending on the system configuration and memory layout. The vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions in software implementations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can be leveraged in active network monitoring environments where tcpdump is commonly deployed. Network administrators and security professionals who rely on tcpdump for packet analysis, intrusion detection, or network troubleshooting may find their systems compromised when processing malicious L2TP traffic. The vulnerability is particularly concerning in environments where tcpdump is run with elevated privileges or in automated monitoring systems that process untrusted network traffic without proper input validation. Attackers could exploit this weakness by sending specially crafted L2TP packets to systems running vulnerable versions of tcpdump, potentially leading to complete system compromise or data exfiltration.
Mitigation strategies for CVE-2017-13006 primarily focus on immediate software updates to tcpdump version 4.9.2 or later, which contain the necessary patches to address the buffer over-read conditions. Organizations should prioritize patching all systems running vulnerable versions of tcpdump, particularly those deployed in network monitoring, security auditing, or forensic analysis roles. Additionally, network administrators should implement proper input validation at network boundaries, using firewalls or intrusion prevention systems to filter suspicious L2TP traffic. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and scripting interpreter, as exploitation could potentially lead to command execution, while the T1499.004 technique for network denial of service represents another operational impact. Security teams should also consider implementing network segmentation and monitoring for unusual L2TP traffic patterns that might indicate exploitation attempts, as well as maintaining comprehensive logging of tcpdump activities for forensic analysis purposes.