CVE-2016-7984 in macOS
Summary
by MITRE
The TFTP parser in tcpdump before 4.9.0 has a buffer overflow in print-tftp.c:tftp_print().
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2016-7984 represents a critical buffer overflow flaw within the Trivial File Transfer Protocol (TFTP) parser of tcpdump software version 4.9.0 and earlier. This issue resides specifically within the print-tftp.c source file at the tftp_print() function, where inadequate input validation and bounds checking allow maliciously crafted TFTP packets to trigger memory corruption. The vulnerability manifests when tcpdump processes TFTP packets during network packet capture and analysis operations, making it exploitable in environments where tcpdump is actively monitoring network traffic. The buffer overflow occurs due to insufficient validation of packet data length before copying data into fixed-size buffers, creating opportunities for attackers to overwrite adjacent memory locations.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where the tftp_print() function fails to properly validate the length of incoming TFTP packet data against the allocated buffer size. When processing TFTP packets, particularly those containing option negotiation or data blocks, the parser directly copies packet contents without adequate bounds checking, allowing an attacker to craft packets with oversized data fields that exceed the predetermined buffer limits. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a common weakness in network protocol parsers where input validation is insufficient. The vulnerability's exploitation potential is heightened by tcpdump's widespread deployment across network monitoring and security analysis environments, where it often runs with elevated privileges to capture network packets.
The operational impact of CVE-2016-7984 extends beyond simple denial of service scenarios to potentially enable remote code execution in vulnerable configurations. When exploited, the buffer overflow can corrupt critical memory structures including return addresses, function pointers, or other program state information, leading to arbitrary code execution or system crashes. Network administrators and security professionals using tcpdump for network monitoring, intrusion detection, or forensic analysis are particularly at risk since the vulnerability can be triggered simply by capturing malicious TFTP traffic. This makes the flaw especially dangerous in environments where tcpdump is deployed for continuous network monitoring, as attackers can remotely compromise systems by sending specially crafted TFTP packets without requiring local access or authentication. The vulnerability's exploitation aligns with ATT&CK technique T1059.007 for command and control communications and T1566 for credential access through network infiltration.
Mitigation strategies for CVE-2016-7984 primarily focus on immediate software updates to tcpdump version 4.9.0 or later, where the buffer overflow has been addressed through proper input validation and bounds checking. System administrators should prioritize patching all affected tcpdump installations across network monitoring infrastructure, security appliances, and forensic analysis systems. Additional defensive measures include implementing network segmentation to isolate critical systems from untrusted network segments, deploying network access controls to filter TFTP traffic, and configuring tcpdump to operate in restricted modes that limit its exposure to malicious packet data. Organizations should also consider implementing network monitoring solutions that can detect and alert on anomalous TFTP packet patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of input validation in network protocol parsers and highlights the need for regular security assessments of network monitoring tools to prevent similar issues in other components of the network security infrastructure.