CVE-2017-13031 in macOS
Summary
by MITRE
The IPv6 fragmentation header parser in tcpdump before 4.9.2 has a buffer over-read in print-frag6.c:frag6_print().
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-13031 represents a critical buffer over-read flaw within the tcpdump network packet analysis tool's IPv6 fragmentation header parser. This issue exists in versions prior to 4.9.2 and specifically affects the print-frag6.c module where the frag6_print() function processes IPv6 fragmentation headers. The flaw arises from inadequate bounds checking during the parsing of fragmented IPv6 packets, creating a scenario where maliciously crafted packets can trigger unauthorized memory access patterns. Such vulnerabilities are particularly dangerous in network monitoring and security analysis contexts where tcpdump is commonly deployed to capture and analyze network traffic. The buffer over-read occurs when the parser attempts to read data beyond the allocated buffer boundaries, potentially exposing sensitive information or enabling further exploitation vectors.
The technical implementation of this vulnerability stems from insufficient validation of fragmentation header fields within the IPv6 protocol processing logic. When tcpdump encounters an IPv6 packet with fragmentation headers, the frag6_print() function fails to properly verify the length of the fragmentation data against available buffer space. This allows an attacker to construct packets with malformed fragmentation headers that cause the parser to access memory locations beyond the intended data boundaries. The vulnerability manifests as a classic buffer over-read condition that falls under CWE-125, which specifically addresses out-of-bounds read vulnerabilities. The flaw can be exploited through network-based attacks where an attacker sends specially crafted IPv6 fragmented packets to a system running vulnerable tcpdump versions, potentially leading to information disclosure or denial of service conditions.
The operational impact of CVE-2017-13031 extends significantly in network security monitoring environments where tcpdump serves as a fundamental tool for packet inspection and analysis. Security professionals and network administrators who rely on tcpdump for intrusion detection, forensic analysis, or network troubleshooting face elevated risks when systems remain vulnerable to this flaw. The vulnerability can be leveraged in various attack scenarios including passive information gathering, where attackers might attempt to extract sensitive data from memory dumps, or active exploitation that could lead to system instability and service disruption. In enterprise environments, this flaw could compromise the integrity of network monitoring infrastructure, potentially allowing attackers to gain insights into network traffic patterns or system memory contents. The vulnerability's exploitation does not require special privileges and can be executed through standard network packet transmission, making it particularly concerning for security tools deployed in critical infrastructure monitoring scenarios.
Mitigation strategies for CVE-2017-13031 primarily focus on updating tcpdump to version 4.9.2 or later, which includes proper bounds checking and buffer validation in the fragmentation header parser. System administrators should conduct immediate vulnerability assessments to identify all systems running affected tcpdump versions and implement patch management procedures to ensure timely updates. Network security teams should also consider implementing additional monitoring measures to detect anomalous packet patterns that might indicate exploitation attempts. The fix addresses the underlying CWE-125 vulnerability by introducing proper input validation and memory boundary checks within the frag6_print() function. Organizations should also review their network monitoring tool configurations and ensure that updated versions are properly tested in their specific environments before deployment. Regular security updates and vulnerability scanning procedures should be maintained to prevent similar issues from arising in other network analysis tools and protocols that may be susceptible to similar buffer over-read conditions.