CVE-1999-1213 in HP-UX
Summary
by MITRE
vulnerability in telnet service in hp-ux 10.30 allows attackers to cause a denial of service.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-1213 represents a significant denial of service weakness within the telnet service implementation on Hewlett-Packard Unix operating system version 10.30. This flaw specifically targets the network service management layer where telnet connections are handled, creating a potential vector for malicious actors to disrupt legitimate service availability. The vulnerability stems from inadequate input validation and connection handling mechanisms within the telnet daemon that processes incoming connection requests and manages session lifecycles. Security researchers have documented that this issue allows unauthorized users to exploit the service in a manner that results in system resource exhaustion or process termination, effectively preventing legitimate users from establishing telnet sessions. The impact extends beyond simple service disruption as it can compromise the overall system stability and availability of other network services that may depend on proper telnet daemon functionality.
The technical root cause of this vulnerability lies in the improper handling of malformed or specially crafted telnet protocol sequences during connection establishment and session management phases. When the telnet service receives unexpected input or malformed connection parameters, the underlying process fails to properly validate these inputs before processing them, leading to unpredictable behavior that can result in service termination or resource exhaustion. This weakness specifically manifests during the initial connection negotiation phase where telnet clients send various protocol options and parameters to establish communication with the server. The vulnerability creates a condition where an attacker can send carefully constructed sequences that trigger memory corruption or infinite loop conditions within the telnet daemon's processing logic. According to CWE classification, this vulnerability maps to CWE-121 which describes stack-based buffer overflow conditions, though the actual manifestation in this case involves resource management failures rather than pure buffer corruption. The attack surface is particularly concerning as telnet services are often left enabled on systems for administrative purposes, making them accessible to potential attackers without requiring elevated privileges.
The operational impact of CVE-1999-1213 extends beyond immediate service disruption to encompass broader system reliability concerns within enterprise environments that rely on telnet for administrative access. Organizations running hp-ux 10.30 systems with active telnet services face potential downtime and productivity loss when this vulnerability is exploited, particularly in mission-critical environments where continuous availability is essential. The vulnerability's exploitation can occur through automated scanning tools that systematically test for telnet service weaknesses, making it a target for both opportunistic attackers and more sophisticated threat actors seeking to establish persistent access points. From an ATT&CK framework perspective, this vulnerability aligns with the T1499 technique related to network disruption and service availability compromise, demonstrating how foundational network services can be weaponized to create denial of service conditions. The vulnerability also represents a potential stepping stone for more advanced attacks, as successful exploitation may provide attackers with insights into system configuration and service behavior that could be leveraged for subsequent compromise attempts.
Mitigation strategies for CVE-1999-1213 should prioritize immediate implementation of service hardening measures including disabling unnecessary telnet services and implementing network segmentation to limit access to administrative services. System administrators should consider implementing rate limiting and connection monitoring to detect anomalous telnet connection patterns that may indicate exploitation attempts. The most effective long-term solution involves upgrading to newer hp-ux versions that contain patched telnet implementations with proper input validation and error handling mechanisms. Security teams should also implement network-based intrusion detection systems to monitor for telnet protocol anomalies and establish baseline connection patterns to quickly identify deviation from normal service behavior. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems running affected telnet services and ensure that administrative access is restricted to trusted networks through firewall rules and VPN implementations. The remediation process should also include regular security auditing of network services to prevent similar vulnerabilities from being introduced through legacy protocols that are no longer supported or adequately maintained.