CVE-2017-12996 in macOS
Summary
by MITRE
The PIMv2 parser in tcpdump before 4.9.2 has a buffer over-read in print-pim.c:pimv2_print().
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Analysis
by VulDB Data Team • 12/05/2025
The vulnerability identified as CVE-2017-12996 represents a critical buffer over-read condition within the Protocol Independent Multicast version 2 parser of tcpdump software. This flaw exists in the print-pim.c source file at the pimv2_print() function, where the software fails to properly validate input data lengths before processing multicast protocol information. The issue arises when tcpdump processes network packets containing PIMv2 headers, specifically during the parsing of multicast routing information that is essential for network monitoring and troubleshooting activities.
The technical implementation of this vulnerability stems from inadequate bounds checking within the packet parsing logic. When tcpdump encounters a PIMv2 packet, it attempts to read data from the packet buffer without first verifying that sufficient data exists beyond the current read position. This oversight allows an attacker to craft malicious packets that contain malformed PIMv2 headers with truncated or unexpected data lengths, causing the parser to read beyond the allocated buffer boundaries. The over-read behavior can result in the program accessing memory locations that were not intended for reading, potentially exposing sensitive information or causing application instability.
From an operational perspective, this vulnerability poses significant risks to network monitoring infrastructure that relies on tcpdump for packet analysis and network troubleshooting. An attacker positioned within the network or capable of injecting malicious packets can exploit this weakness to either crash the tcpdump process, leading to denial of service conditions, or potentially extract information from adjacent memory regions. The impact extends beyond simple service disruption as the over-read could inadvertently expose sensitive data such as cryptographic keys, passwords, or other confidential information stored in memory adjacent to the affected buffer. This vulnerability is particularly concerning in environments where tcpdump is used for security monitoring, forensic analysis, or network traffic capture in production environments.
The vulnerability aligns with CWE-129, which describes improper validation of length of inputs to ensure they are within expected ranges, and can be mapped to ATT&CK technique T1059.007 for the execution of malicious payloads through network protocols. Organizations using tcpdump versions prior to 4.9.2 should immediately implement mitigation strategies including software updates to the patched version, network segmentation to limit exposure, and monitoring for suspicious packet patterns that might indicate exploitation attempts. Additionally, implementing proper input validation mechanisms and conducting regular security assessments of network monitoring tools will help prevent similar vulnerabilities from being exploited in other components of the network infrastructure.