CVE-2017-12899 in macOS
Summary
by MITRE
The DECnet parser in tcpdump before 4.9.2 has a buffer over-read in print-decnet.c:decnet_print().
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-12899 represents a critical buffer over-read flaw within the DECnet protocol parser of tcpdump software version 4.9.1 and earlier. This issue manifests in the print-decnet.c source file at the decnet_print() function, where improper input validation allows maliciously crafted network packets to trigger memory access violations. The DECnet protocol, historically used for network communications in digital equipment networks, remains supported in tcpdump for legacy network analysis purposes, making this vulnerability particularly concerning for security professionals maintaining older network infrastructures.
The technical implementation of this vulnerability stems from insufficient bounds checking within the packet parsing logic. When tcpdump processes network traffic containing DECnet protocol data, the decnet_print() function fails to properly validate the length of incoming data segments before attempting to read from memory locations. This allows an attacker to craft specially formatted packets that cause the parser to access memory beyond the allocated buffer boundaries, potentially leading to information disclosure, application crashes, or in some scenarios, arbitrary code execution. The vulnerability specifically affects the handling of DECnet datagrams where the parser assumes certain minimum data lengths without proper validation, creating a predictable over-read condition.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios, as it presents potential security risks for network monitoring and analysis environments. Organizations relying on tcpdump for network traffic analysis, intrusion detection, or forensic investigations may experience system instability when processing maliciously crafted DECnet traffic. The vulnerability is particularly dangerous in environments where tcpdump is used for continuous network monitoring, as a single malicious packet could cause the monitoring system to crash, potentially creating blind spots in network security. Additionally, the over-read condition may expose sensitive memory contents to attackers, potentially revealing system information or credentials that could be leveraged for further attacks.
Mitigation strategies for CVE-2017-12899 primarily focus on immediate software updates to tcpdump version 4.9.2 or later, which contains the necessary patches to address the buffer over-read condition. Security administrators should prioritize patching affected systems, particularly those running legacy network monitoring infrastructure that continues to support DECnet protocol analysis. Network segmentation and access controls should be implemented to limit exposure to potentially malicious traffic, while monitoring systems should be configured to detect and alert on unusual packet patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and could potentially be leveraged by threat actors following ATT&CK technique T1046 for network service scanning or T1059 for command and scripting interpreter usage, making comprehensive network monitoring essential for early detection of exploitation attempts.