CVE-2016-7993 in macOS
Summary
by MITRE
A bug in util-print.c:relts_print() in tcpdump before 4.9.0 could cause a buffer overflow in multiple protocol parsers (DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, PIM).
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2016-7993 represents a critical buffer overflow flaw within the tcpdump network packet analysis tool that affected versions prior to 4.9.0. This issue resides in the util-print.c file within the relts_print() function, which serves as a core component responsible for formatting and displaying network protocol information during packet captures. The flaw manifests when tcpdump processes packets containing malformed or specially crafted data structures that exceed the allocated buffer boundaries during protocol parsing operations. The vulnerability specifically impacts multiple widely used network protocols including DNS, DVMRP, HSRP, IGMP, lightweight resolver protocol, and PIM, making it particularly dangerous as it can affect various network infrastructure components and services that rely on proper packet analysis.
The technical implementation of this buffer overflow stems from inadequate input validation and boundary checking within the protocol parsing routines. When tcpdump encounters network packets with unexpected data lengths or malformed structures, the relts_print() function fails to properly constrain string operations and memory allocations, allowing attackers to write beyond the intended buffer limits. This condition creates a classic stack-based buffer overflow scenario where adjacent memory regions become corrupted, potentially leading to arbitrary code execution or application crashes. The vulnerability is particularly concerning because tcpdump is commonly used by network administrators, security professionals, and forensic analysts in both production environments and security testing scenarios, meaning that exploitation could compromise the integrity of network monitoring systems.
The operational impact of CVE-2016-7993 extends beyond simple application instability to encompass potential security breaches and service disruption. Attackers could exploit this vulnerability by crafting malicious network packets that trigger the buffer overflow when processed by tcpdump, potentially enabling remote code execution on systems running vulnerable versions of the tool. This risk is amplified in environments where tcpdump is used for real-time network monitoring, intrusion detection, or security auditing purposes, as compromised monitoring tools could provide attackers with unauthorized access to network traffic data or enable them to bypass security controls. The vulnerability affects systems where tcpdump is deployed in network security appliances, firewall configurations, and network forensic analysis workstations, making it a significant concern for enterprise network security infrastructure.
Mitigation strategies for CVE-2016-7993 primarily focus on immediate version upgrades to tcpdump 4.9.0 or later, which contain the necessary patches to address the buffer overflow conditions. Network administrators should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions of tcpdump and implement remediation procedures as quickly as possible. Additionally, organizations should consider implementing network segmentation and access controls to limit exposure, while also monitoring for suspicious network activity that might indicate exploitation attempts. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and falls under ATT&CK technique T1046 for network service scanning and T1059 for command and scripting interpreter usage, as exploitation could enable attackers to gain persistent access to network monitoring systems and potentially escalate privileges within the network infrastructure.