CVE-2017-5486 in macOS
Summary
by MITRE
The ISO CLNS parser in tcpdump before 4.9.0 has a buffer overflow in print-isoclns.c:clnp_print().
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2017-5486 represents a critical buffer overflow flaw within the tcpdump network analysis tool suite. This issue specifically affects the ISO CLNS (Connectionless Network Service) parser component, which is responsible for interpreting and displaying network traffic that utilizes the OSI network layer protocols. The vulnerability manifests in the print-isoclns.c source file at the clnp_print() function, where insufficient input validation and boundary checking allow maliciously crafted network packets to trigger memory corruption conditions. The affected version range includes tcpdump versions prior to 4.9.0, making a substantial portion of deployed network monitoring tools susceptible to this weakness.
The technical nature of this buffer overflow stems from improper handling of packet data structures within the CLNS protocol implementation. When tcpdump processes network traffic containing ISO CLNS frames, the clnp_print() function fails to adequately validate the length of incoming data before copying it into fixed-size buffers. This classic programming error allows attackers to craft specially formatted packets that exceed the allocated buffer space, resulting in memory overwrite conditions that can be exploited to execute arbitrary code on systems running vulnerable versions of tcpdump. The vulnerability falls under the CWE-121 category of stack-based buffer overflow, representing a fundamental flaw in memory management practices within the network protocol parsing code.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution capabilities. Network administrators who rely on tcpdump for traffic analysis and monitoring are at risk when processing packets from untrusted sources, particularly in environments where network monitoring tools operate in promiscuous mode or when analyzing captured traffic from potentially malicious networks. The vulnerability can be exploited through network traffic analysis sessions where attackers send malformed CLNS packets to systems running vulnerable tcpdump versions, potentially allowing remote attackers to gain unauthorized access to the monitoring systems or disrupt network operations. This weakness is particularly concerning in enterprise environments where tcpdump is commonly used for security monitoring, network troubleshooting, and forensic analysis activities.
Mitigation strategies for CVE-2017-5486 primarily focus on immediate version updates to tcpdump 4.9.0 or later releases, which contain the necessary patches to address the buffer overflow conditions in the CLNS parser. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while deploying intrusion detection systems that can identify and block malformed network packets. The vulnerability demonstrates the importance of maintaining up-to-date network security tools and implementing proper input validation in protocol parsing components. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving remote code execution through software exploitation and can be classified under the T1203 sub-technique for Exploitation for Client Execution, emphasizing the need for comprehensive vulnerability management programs that address both known and emerging threats in network monitoring infrastructure.