CVE-2017-13017 in macOS
Summary
by MITRE
The DHCPv6 parser in tcpdump before 4.9.2 has a buffer over-read in print-dhcp6.c:dhcp6opt_print().
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-13017 represents a critical buffer over-read flaw within the dhcp6opt_print function of tcpdump's DHCPv6 parser implementation. This issue affects tcpdump versions prior to 4.9.2 and specifically manifests in the print-dhcp6.c source file where the DHCPv6 option parsing routine fails to properly validate input data lengths before attempting to read from memory buffers. The flaw occurs when tcpdump processes DHCPv6 packets containing malformed or crafted option data structures, leading to unauthorized memory access patterns that can result in application crashes or potentially exploitable conditions. Such vulnerabilities in network protocol analyzers pose significant risks to network security operations since these tools are commonly deployed in security monitoring and incident response scenarios.
The technical implementation of this vulnerability stems from inadequate bounds checking within the dhcp6opt_print function which processes DHCPv6 options without sufficient validation of the option length fields present in the parsed packets. When encountering DHCPv6 packets with malformed option structures, particularly those with option lengths that exceed expected boundaries or contain invalid values, the parser continues to read beyond allocated buffer boundaries. This over-read behavior can access adjacent memory regions, potentially exposing sensitive data or causing the application to terminate abnormally. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of insufficient input validation in network protocol parsing code. The flaw is particularly concerning because DHCPv6 is a fundamental protocol for IPv6 network configuration and management, making it a common target for both legitimate network monitoring and malicious packet crafting activities.
The operational impact of this vulnerability extends beyond simple application instability to potentially compromise network security monitoring capabilities and create attack vectors for sophisticated adversaries. When tcpdump encounters maliciously crafted DHCPv6 packets in its capture stream, the buffer over-read can cause the tool to crash, resulting in loss of network monitoring data and potential denial of service for security operations teams relying on continuous network traffic analysis. In more severe scenarios, if an attacker can control the memory contents accessed through this over-read condition, it may be possible to achieve arbitrary code execution within the tcpdump process context. This vulnerability directly impacts the ATT&CK technique T1046 which involves network service scanning, as attackers could use this flaw to disrupt network monitoring infrastructure while conducting reconnaissance activities. Security analysts and network administrators using tcpdump for network traffic analysis and forensic investigations face significant risk when operating vulnerable versions, as the tool may fail during critical security events or incident response activities.
Mitigation strategies for CVE-2017-13017 primarily involve immediate patching of tcpdump installations to version 4.9.2 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should prioritize updating their network monitoring and security tools to address this vulnerability, particularly those environments where tcpdump is used in security-critical roles such as intrusion detection systems, network forensics tools, or security information and event management platforms. Additional defensive measures include implementing network segmentation to limit exposure to potentially malicious DHCPv6 traffic, deploying network access control measures to restrict DHCPv6 packet processing, and monitoring for unusual tcpdump process behavior or crashes that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation in network protocol parsing code and highlights the need for regular security updates to maintain the integrity of essential network monitoring infrastructure. Organizations should also consider implementing network-based intrusion detection systems that can detect and block malformed DHCPv6 traffic patterns that may be used to exploit this class of vulnerability.