CVE-2016-7940 in macOS
Summary
by MITRE
The STP parser in tcpdump before 4.9.0 has a buffer overflow in print-stp.c, multiple functions.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2016-7940 represents a critical buffer overflow flaw within the Spanning Tree Protocol (STP) parser of tcpdump software versions prior to 4.9.0. This issue manifests specifically in the print-stp.c source file where multiple functions fail to properly validate input data lengths before processing STP protocol frames. The buffer overflow occurs when tcpdump encounters specially crafted STP packets that exceed the allocated buffer space during parsing operations, creating potential avenues for arbitrary code execution or system compromise.
The technical implementation of this vulnerability stems from inadequate bounds checking within the STP packet parsing logic. When tcpdump processes incoming network packets containing STP information, the parser attempts to extract and display various protocol parameters including bridge identifiers, port roles, and state information. The flaw arises because the code does not sufficiently validate the length of incoming STP data structures before copying them into fixed-size buffers, allowing attackers to craft malicious STP frames that overflow these buffers and potentially overwrite adjacent memory regions.
This vulnerability directly maps to CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The operational impact of CVE-2016-7940 extends beyond simple denial of service scenarios, as the buffer overflow could potentially be exploited to execute arbitrary code on systems running vulnerable tcpdump versions. Network administrators who rely on tcpdump for network monitoring and analysis face significant risk exposure, particularly in environments where untrusted network traffic is processed without proper filtering mechanisms.
The attack surface for this vulnerability is particularly concerning given tcpdump's widespread deployment across network monitoring and security auditing systems. Attackers could exploit this weakness by transmitting maliciously crafted STP frames to networks where vulnerable tcpdump instances are running, potentially leading to complete system compromise. The vulnerability's exploitation aligns with ATT&CK technique T1059.007 for command and control communications, as compromised systems could be used to establish persistent access or relay attacks within network infrastructures. Organizations utilizing tcpdump for security monitoring, intrusion detection, or network forensics should consider this vulnerability as a critical threat requiring immediate remediation through version updates.
Mitigation strategies for CVE-2016-7940 primarily involve upgrading tcpdump to version 4.9.0 or later, which contains patches addressing the buffer overflow conditions in the STP parser. Network administrators should also implement additional defensive measures including network segmentation, access control lists, and monitoring for unusual STP traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date network security tools and highlights the need for comprehensive input validation across all network protocol parsers to prevent similar issues in other network monitoring applications.