CVE-1999-0221 in Ascend Router
Summary
by MITRE
Denial of service of Ascend routers through port 150 (remote administration).
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability described in CVE-1999-0221 represents a critical denial of service weakness in Ascend routers that specifically targets the remote administration port 150. This flaw allows remote attackers to disrupt network services by exploiting a vulnerability in the router's administrative interface, potentially causing complete service interruption for network administrators and end users. The issue stems from the router's improper handling of incoming connections on the designated port, creating a pathway for malicious actors to compromise network availability and operational continuity. This vulnerability directly impacts the reliability and security posture of networks relying on Ascend router infrastructure.
The technical implementation of this vulnerability involves a specific flaw in how the Ascend router processes incoming connections on port 150, which serves as the designated remote administration port for network configuration and management tasks. When an attacker sends malformed or specially crafted packets to this port, the router's processing mechanism fails to properly validate or handle the incoming data, leading to system instability and eventual service disruption. This type of vulnerability typically falls under CWE-122, which describes buffer overflow conditions, or CWE-129, which addresses improper validation of input parameters. The flaw likely occurs during the parsing or handling of administrative commands, where insufficient input validation allows the system to crash or become unresponsive when encountering unexpected data patterns.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire network infrastructure's management capabilities. Network administrators who rely on remote access for router configuration and monitoring would lose access to critical management functions, forcing them to resort to physical access or alternative recovery procedures that can take considerable time to implement. This disruption affects the availability of network services and can result in significant downtime for organizations depending on Ascend routers for their network operations. The vulnerability particularly impacts enterprise networks where remote administration is essential for maintaining operational efficiency and where network downtime can result in substantial financial losses and service interruptions.
Mitigation strategies for this vulnerability require immediate implementation of network segmentation and access control measures to restrict access to port 150 from unauthorized sources. Organizations should implement firewall rules to limit connections to the administrative port to trusted IP addresses only, while also considering disabling the remote administration service entirely if local management is sufficient for their operational requirements. The most effective long-term solution involves applying vendor-provided patches or firmware updates that address the specific input validation flaws in the router's administrative interface. Network administrators should also implement monitoring solutions to detect unusual connection patterns on port 150 and establish incident response procedures that can quickly address potential exploitation attempts. This vulnerability aligns with attack patterns documented in the attack technique T1190, which describes exploitation of remote services, and demonstrates the importance of maintaining up-to-date security configurations and implementing defense-in-depth strategies to protect critical network infrastructure components.