CVE-2016-7973 in macOS
Summary
by MITRE
The AppleTalk parser in tcpdump before 4.9.0 has a buffer overflow in print-atalk.c, multiple functions.
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2016-7973 represents a critical buffer overflow flaw within the AppleTalk protocol parser of tcpdump version 4.8.2 and earlier. This issue resides specifically in the print-atalk.c source file and affects multiple functions within the network packet analysis tool. The vulnerability stems from inadequate input validation and bounds checking when processing AppleTalk protocol packets, creating a scenario where maliciously crafted packets can trigger memory corruption. AppleTalk, a legacy networking protocol developed by Apple Inc., was historically used in early macintosh networks and remains supported for backward compatibility in modern network analysis tools. The buffer overflow condition occurs when tcpdump attempts to parse AppleTalk frames that exceed the allocated buffer space, leading to potential memory overwrite scenarios that could compromise the integrity of the network monitoring process.
The technical exploitation of this vulnerability involves sending specially crafted AppleTalk packets to a system running an affected version of tcpdump. When the parser encounters these malformed packets, the lack of proper bounds checking causes data to be written beyond the allocated memory buffer, potentially overwriting adjacent memory locations. This memory corruption can lead to arbitrary code execution, denial of service conditions, or information disclosure depending on the specific memory regions affected. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read vulnerabilities. The attack surface is particularly concerning for network administrators who rely on tcpdump for network monitoring and security analysis, as the tool typically runs with elevated privileges to capture network traffic.
The operational impact of CVE-2016-7973 extends beyond simple denial of service scenarios, as it creates potential entry points for more sophisticated attacks within network monitoring environments. Network security professionals using tcpdump for traffic analysis, intrusion detection, or forensic investigations face significant risk when systems are exposed to unfiltered network traffic containing malicious AppleTalk packets. The vulnerability affects not only direct network monitoring but also any automated security tools that depend on tcpdump for packet processing, potentially compromising security infrastructure. According to ATT&CK framework tactic TA0005 (Defense Evasion), this vulnerability could be leveraged to evade network monitoring by corrupting the analysis tool itself, while potentially supporting TA0002 (Execution) if the buffer overflow results in code execution. The vulnerability is particularly dangerous in environments where tcpdump is used for security auditing or network forensics, as attackers could exploit it to compromise the very tools designed to detect malicious activity.
Mitigation strategies for CVE-2016-7973 require immediate patching of tcpdump installations to version 4.9.0 or later, where the buffer overflow has been addressed through proper input validation and bounds checking. Network administrators should implement network segmentation and filtering to prevent unauthorized AppleTalk traffic from reaching systems running tcpdump, particularly in environments where legacy AppleTalk protocols are not required. Additional protective measures include deploying network intrusion prevention systems that can detect and block malformed AppleTalk packets, implementing strict access controls for systems running tcpdump, and conducting regular vulnerability assessments to identify other potentially affected network monitoring tools. The fix implemented in tcpdump 4.9.0 demonstrates proper defensive programming practices, including bounds checking, input validation, and memory management improvements that align with secure coding standards. Organizations should also consider implementing network traffic monitoring with multiple layers of security controls, as relying solely on a single tool for network analysis creates a single point of failure that could be exploited through vulnerabilities like CVE-2016-7973.