CVE-2000-0041 in Mac OS
Summary
by MITRE
Macintosh systems generate large ICMP datagrams in response to malformed datagrams, allowing them to be used as amplifiers in a flood attack.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability described in CVE-2000-0041 represents a critical flaw in Apple Macintosh systems that enables malicious actors to exploit the network stack's response behavior during ICMP packet processing. This weakness stems from the system's improper handling of malformed Internet Control Message Protocol datagrams, where the operating system generates disproportionately large response packets instead of gracefully discarding the malformed input. The flaw exists at the network protocol implementation level within the Macintosh operating system's ICMP handling mechanisms, creating an amplification factor that makes these systems particularly susceptible to distributed denial-of-service attacks.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and CWE-400, which covers resource exhaustion vulnerabilities. When a malformed ICMP datagram is received by a vulnerable Macintosh system, the network stack fails to properly validate the packet structure and instead processes the malformed data in a way that triggers the generation of large response packets. These response packets can be hundreds or thousands of times larger than the original malformed packet, creating an ideal scenario for amplification attacks. The vulnerability specifically affects systems running older versions of Mac OS, where the ICMP implementation lacks proper bounds checking and input sanitization mechanisms.
The operational impact of this vulnerability is severe and directly enables attackers to leverage Macintosh systems as amplifiers in larger-scale network attacks. In a typical flood attack scenario, an attacker can send a small malformed ICMP packet to a vulnerable Macintosh system, causing it to respond with a much larger packet that is then forwarded to the intended victim. This amplification effect allows attackers to generate massive amounts of traffic with minimal resources, potentially overwhelming network infrastructure and causing legitimate service disruption. The vulnerability particularly affects systems that are exposed to the internet or have open network connections, making it a significant concern for organizations with Macintosh deployments in network-accessible environments.
Mitigation strategies for CVE-2000-0041 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should implement network-level filtering to drop malformed ICMP packets at perimeter devices, particularly those with large payload sizes that exceed normal ICMP packet boundaries. Network administrators should also consider disabling ICMP responses on systems that do not require them for legitimate network operations, as outlined in the ATT&CK framework's mitigation techniques for network denial of service. The most effective long-term solution involves upgrading to newer versions of Mac OS that contain proper input validation and bounds checking for ICMP packet processing, along with implementing comprehensive network monitoring to detect unusual ICMP traffic patterns that may indicate exploitation attempts. Additionally, organizations should consider network segmentation and access control measures to limit exposure of vulnerable Macintosh systems to external network traffic.