CVE-1999-0919 in CableRouter
Summary
by MITRE
A memory leak in a Motorola CableRouter allows remote attackers to conduct a denial of service via a large number of telnet connections.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-0919 represents a critical memory management flaw in Motorola CableRouter devices that enables remote attackers to execute denial of service attacks through excessive telnet connection attempts. This issue stems from inadequate resource handling within the router's telnet service implementation, where each connection attempt consumes system memory without proper cleanup mechanisms. The vulnerability specifically affects the router's ability to manage concurrent telnet sessions, creating a condition where successive connection attempts gradually deplete available memory resources until the device becomes unresponsive or crashes entirely.
The technical root cause of this memory leak resides in the router's telnet daemon implementation which fails to properly release allocated memory buffers after connection handling. When multiple telnet connections are established simultaneously or in rapid succession, the system accumulates memory fragments that cannot be effectively reclaimed by the memory management subsystem. This condition aligns with CWE-401, which categorizes memory leaks as weaknesses in software systems where allocated memory is not properly deallocated, leading to progressive resource exhaustion. The vulnerability operates at the application layer of the network stack, specifically targeting the telnet service that provides remote administrative access to the router configuration interface.
From an operational perspective, this vulnerability poses significant risks to network infrastructure reliability and availability. Remote attackers can exploit this weakness by establishing numerous concurrent telnet connections to overwhelm the router's memory capacity, effectively rendering the device unusable for legitimate network operations. The impact extends beyond simple service disruption as it can compromise network management capabilities, potentially affecting critical network services that depend on the router's functionality. This attack vector demonstrates the importance of proper resource management in embedded network devices and highlights how seemingly benign services like telnet can become attack vectors when memory handling is inadequate.
The security implications of CVE-1999-0919 align with several tactics outlined in the MITRE ATT&CK framework, particularly those related to denial of service operations and privilege escalation through service exploitation. Attackers can leverage this vulnerability to disrupt network communications without requiring elevated privileges or specialized tools, making it an attractive target for malicious actors seeking to compromise network availability. The vulnerability also reflects poor defensive practices in embedded system development where resource management is often overlooked in favor of functional completeness. Network administrators should consider implementing connection rate limiting and monitoring for unusual telnet connection patterns as part of their defensive strategies against this type of memory exhaustion attack.
Mitigation strategies for this vulnerability should focus on both immediate operational responses and long-term architectural improvements. Immediate actions include disabling unnecessary telnet services and implementing connection throttling mechanisms to limit the number of concurrent telnet sessions. Network administrators should also establish monitoring protocols to detect unusual connection patterns that may indicate exploitation attempts. The underlying memory management issues require firmware updates from Motorola that properly implement memory cleanup routines and connection handling protocols. Organizations should also consider implementing network segmentation and access control measures to limit exposure of vulnerable router devices to unauthorized network access. Additionally, regular security assessments of network infrastructure should include evaluation of memory management practices in embedded devices to identify similar vulnerabilities before they can be exploited by attackers.