CVE-2017-13021 in macOS
Summary
by MITRE
The ICMPv6 parser in tcpdump before 4.9.2 has a buffer over-read in print-icmp6.c:icmp6_print().
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-13021 represents a critical buffer over-read flaw within the ICMPv6 parser implementation of tcpdump version 4.9.1 and earlier. This issue manifests specifically in the print-icmp6.c source file at the icmp6_print() function where the software fails to properly validate input data length before attempting to read from memory buffers. The flaw occurs when tcpdump processes IPv6 packets containing ICMPv6 headers, creating a scenario where maliciously crafted packets can trigger unauthorized memory access patterns. The vulnerability stems from inadequate bounds checking mechanisms that allow the parser to read beyond the allocated buffer boundaries, potentially exposing sensitive memory contents or causing application instability.
The technical exploitation of this vulnerability involves sending specially crafted ICMPv6 packets to a system running an affected version of tcpdump in promiscuous mode or when capturing network traffic containing IPv6 communications. When the tcpdump utility processes these malformed packets, the icmp6_print() function attempts to read memory locations beyond the intended data buffer, leading to undefined behavior that may result in application crashes, information disclosure, or potentially remote code execution depending on the system configuration and memory layout. This type of vulnerability falls under the CWE-129 weakness category, specifically addressing improper validation of buffer boundaries, and aligns with ATT&CK technique T1059.007 for execution through network protocols. The buffer over-read condition creates a path for attackers to potentially extract sensitive information from memory or cause denial of service conditions that disrupt network monitoring capabilities.
The operational impact of CVE-2017-13021 extends beyond simple application crashes to affect network security monitoring and forensic analysis operations that rely on tcpdump for packet capture and analysis. Organizations using tcpdump for network intrusion detection, security auditing, or network troubleshooting may experience service disruption when processing malicious traffic, potentially masking actual security incidents or creating false negatives in threat detection systems. The vulnerability is particularly concerning in environments where tcpdump is used for continuous network monitoring, as attackers could exploit this flaw to cause persistent service disruptions or to gain unauthorized access to network monitoring infrastructure. Security professionals must consider the cascading effects of such vulnerabilities on network defense systems, as compromised monitoring tools may no longer provide reliable data for incident response activities. The flaw demonstrates the critical importance of input validation in network protocol parsers and highlights the need for comprehensive security testing of network utilities used in production environments.
Mitigation strategies for CVE-2017-13021 primarily involve upgrading to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition in the ICMPv6 parser. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while monitoring for unusual network activity that might indicate exploitation attempts. Additional defensive measures include deploying intrusion detection systems with signature updates that can detect and block malicious ICMPv6 traffic patterns, implementing network access control lists to filter problematic packets at network boundaries, and conducting regular security assessments of network monitoring infrastructure. Organizations should also consider using alternative packet analysis tools that have been verified to contain similar security fixes, while ensuring that all network monitoring equipment undergoes regular security updates and vulnerability assessments. The remediation process should include thorough testing of updated software in controlled environments before deployment to production systems to ensure compatibility with existing network monitoring workflows and configurations.