CVE-1999-0128 in Linux
Summary
by MITRE
Oversized ICMP ping packets can result in a denial of service, aka Ping o' Death.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0128 represents one of the earliest and most significant denial of service exploits targeting network protocols. This issue specifically affects the Internet Control Message Protocol implementation in various operating systems, particularly those based on unix-like architectures. The vulnerability manifests when systems process oversized ICMP echo request packets that exceed normal packet size limitations, creating a condition where the receiving system becomes overwhelmed and unable to properly handle network traffic. This flaw directly impacts the fundamental network communication mechanisms that underpin internet connectivity and system availability.
The technical root cause of this vulnerability lies in the improper handling of ICMP packet fragmentation and reassembly processes within network stacks. When an attacker sends an oversized ICMP ping packet, typically exceeding the maximum transmission unit size of 65535 bytes, the receiving system attempts to process and reassemble these fragments. The flaw occurs because the system does not properly validate the packet size limits or implement adequate buffer management during the reassembly process. This results in memory allocation issues where the system attempts to allocate buffers larger than available memory or creates corrupted data structures during packet processing. The vulnerability is categorized under CWE-122 as "Heap-based Buffer Overflow" and is also related to CWE-129 as "Improper Validation of Array Index" since the system fails to validate packet boundaries and array access limits during reassembly operations.
The operational impact of this vulnerability extends far beyond simple service disruption, as it can affect entire network infrastructure and critical systems. When exploited successfully, the Ping of Death attack can cause target systems to crash, reboot, or become unresponsive to legitimate network traffic. This creates cascading effects throughout networked environments where dependent systems may also fail due to the loss of connectivity. The attack vector is particularly dangerous because ICMP ping is a fundamental network diagnostic tool that is enabled by default on virtually all operating systems, making the vulnerability accessible to attackers with minimal technical expertise. According to ATT&CK framework, this vulnerability maps to T1498 as "Network Denial of Service" and T1595 as "Active Scanning" since attackers can easily identify vulnerable systems and exploit them systematically. The attack can be executed from any location with network access, making it a particularly effective tool for disrupting services without requiring physical access or sophisticated attack infrastructure.
Mitigation strategies for this vulnerability require both immediate system-level fixes and long-term architectural improvements to network security. The most effective immediate solution involves implementing proper packet size validation and limiting the maximum ICMP packet size that systems will accept or process. Network administrators should configure firewalls and routers to filter oversized ICMP packets at network boundaries, preventing these malformed packets from reaching vulnerable systems. Operating system vendors addressed this issue through patches that modified the ICMP processing code to properly validate packet sizes and implement robust buffer management. The implementation of ingress and egress filtering rules, combined with regular system updates and security audits, provides comprehensive protection against this type of attack. Additionally, monitoring network traffic for unusual ICMP packet patterns and implementing intrusion detection systems can help identify and block exploitation attempts before they cause significant damage to network availability.