CVE-2017-5485 in macOS
Summary
by MITRE
The ISO CLNS parser in tcpdump before 4.9.0 has a buffer overflow in addrtoname.c:lookup_nsap().
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2017-5485 represents a critical buffer overflow flaw within the tcpdump network packet analysis tool that affects versions prior to 4.9.0. This issue specifically resides in the ISO CLNS (Connectionless Network Service) parser implementation, which is responsible for interpreting network addresses and routing information within the OSI network model. The buffer overflow occurs in the addrtoname.c source file at the lookup_nsap() function, indicating a fundamental flaw in how tcpdump processes and validates network address information. The vulnerability stems from inadequate bounds checking when handling network address data, particularly in the context of NSAP (Network Service Access Point) address parsing which is essential for OSI network communication protocols.
The technical nature of this vulnerability places it squarely within the category of memory corruption flaws that can be exploited to execute arbitrary code or cause denial of service conditions. When tcpdump encounters network packets containing malformed NSAP addresses, the lookup_nsap() function fails to properly validate input data length against allocated buffer boundaries. This allows an attacker to craft malicious network packets that, when processed by the vulnerable tcpdump version, can overwrite adjacent memory locations. The flaw manifests as a classic stack-based buffer overflow scenario where insufficient input validation permits data to exceed the allocated buffer space, potentially corrupting program execution flow and creating opportunities for privilege escalation or remote code execution. This vulnerability directly maps to CWE-121, which describes stack-based buffer overflow conditions, and represents a significant risk in network monitoring and security analysis environments where tcpdump is commonly deployed.
The operational impact of CVE-2017-5485 extends beyond simple denial of service scenarios to encompass potential compromise of network monitoring systems that rely on tcpdump for packet analysis. Security operations centers and network administrators who deploy vulnerable tcpdump versions in production environments face elevated risk of unauthorized access when processing network traffic containing maliciously crafted packets. The vulnerability is particularly concerning in environments where tcpdump is used for security monitoring, intrusion detection, or network forensics, as attackers could exploit this flaw to gain control over monitoring systems or disrupt network analysis operations. This creates a significant risk for organizations that depend on tcpdump for network traffic inspection and security auditing activities, potentially compromising their ability to detect and respond to security incidents. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and control through network protocols, as the exploitation could enable attackers to establish persistent access through compromised monitoring infrastructure.
Mitigation strategies for CVE-2017-5485 focus primarily on upgrading to tcpdump version 4.9.0 or later, which contains the necessary patches to address the buffer overflow condition in the lookup_nsap() function. Organizations should conduct immediate inventory assessments to identify all systems running vulnerable tcpdump versions and prioritize patch deployment across their network infrastructure. Network administrators should also implement additional defensive measures such as restricting tcpdump execution privileges, monitoring for suspicious packet patterns, and employing network segmentation to limit potential attack vectors. The fix implemented in the patched versions typically involves adding proper input validation and bounds checking to ensure that NSAP address data cannot exceed allocated buffer boundaries during processing. Security teams should also consider implementing network-based intrusion prevention systems that can detect and block malformed packets designed to exploit this vulnerability, while maintaining regular vulnerability assessments to identify similar issues in other network analysis tools and security infrastructure components.