CVE-2018-14461 in tcpdump
Summary
by MITRE
The LDP parser in tcpdump before 4.9.3 has a buffer over-read in print-ldp.c:ldp_tlv_print().
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Analysis
by VulDB Data Team • 12/03/2025
The vulnerability identified as CVE-2018-14461 represents a critical buffer over-read flaw within the Label Distribution Protocol parser of tcpdump software versions prior to 4.9.3. This issue specifically manifests in the print-ldp.c source file at the ldp_tlv_print() function, where improper input validation allows attackers to craft malicious network packets that trigger memory access violations. The flaw occurs when tcpdump processes Label Distribution Protocol messages, which are fundamental components of Multiprotocol Label Switching networks used for label distribution between routers. The buffer over-read vulnerability arises from insufficient bounds checking when processing TLV (Type-Length-Value) structures within LDP protocol messages, creating opportunities for memory corruption that could potentially lead to arbitrary code execution or service disruption.
The technical implementation of this vulnerability stems from the tcpdump application's failure to properly validate the length field of TLV structures before attempting to read data from memory locations. When an attacker sends a malformed LDP packet containing oversized or malformed TLV elements, the ldp_tlv_print() function attempts to read beyond the allocated buffer boundaries, resulting in over-read conditions that can expose sensitive memory contents or cause application crashes. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that occur when software attempts to access memory beyond the intended buffer limits. The vulnerability demonstrates characteristics consistent with the attack pattern described in MITRE ATT&CK technique T1059.007 for command and control communications, as the over-read could potentially be leveraged to extract memory addresses or other sensitive information that might aid in further exploitation attempts.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios, as it represents a potential vector for more sophisticated attacks targeting network infrastructure components that rely on tcpdump for packet analysis. Network administrators and security professionals who use tcpdump for monitoring LDP-enabled networks are particularly at risk since the vulnerability can be triggered by simply capturing and processing malicious LDP packets. The affected environment includes any system running tcpdump versions before 4.9.3 that processes LDP traffic, which encompasses routers, network monitoring appliances, and security tools that utilize tcpdump for protocol analysis. This vulnerability could be exploited in conjunction with other network-based attacks to compromise network infrastructure, as the over-read condition might reveal memory layout information or sensitive data that could be used to bypass security controls or facilitate privilege escalation attacks. Organizations using tcpdump for network traffic analysis should consider this vulnerability as part of their broader network security posture assessment, particularly in environments where LDP protocol traffic is present and monitored.
The recommended mitigation strategy involves upgrading tcpdump to version 4.9.3 or later, which includes proper bounds checking and input validation for LDP TLV structures. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious LDP traffic, while monitoring for unusual LDP packet patterns that might indicate exploitation attempts. Additional defensive measures include deploying network intrusion detection systems that can identify malformed LDP traffic and implementing proper input sanitization at network boundaries. Organizations should conduct vulnerability assessments to identify systems running vulnerable versions of tcpdump and prioritize patching based on network exposure and criticality. The fix implemented in tcpdump 4.9.3 addresses the root cause by introducing proper validation of TLV length fields before memory access operations, preventing the buffer over-read condition that previously allowed attackers to manipulate memory access patterns through carefully crafted LDP packets.