CVE-2026-76662 in NonStop TELSERV
Summary
by MITRE • 10/15/2026
A buffer overflow vulnerability in HPE NonStop TELSERV can cause memory corruption and DoS.
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Analysis
by VulDB Data Team • 10/15/2026
The HighPoint Enterprise (HPE) NonStop operating system, specifically within the TELSERV component responsible for handling terminal server connections, contains a critical buffer overflow vulnerability that poses significant risks to system integrity and availability. This flaw arises from insufficient validation of input data lengths during the processing of network-based connection requests or configuration parameters sent by clients attempting to establish sessions with the Telnet service. When an attacker crafts a maliciously formatted packet containing payload data exceeding the expected buffer size, the application fails to properly bound-check this input before writing it to memory. This lack of rigorous boundary checking allows the excess data to overwrite adjacent memory locations, leading directly to heap or stack corruption depending on the specific allocation strategy employed by TELSERV during session initialization.
The immediate operational impact of this vulnerability is primarily a denial of service condition for affected systems. As the buffer overflow corrupts critical control structures within the process memory space, it typically causes the TELSERV daemon to crash abruptly. Since NonStop architectures rely heavily on continuous availability and fault tolerance mechanisms, the failure of such a core networking component can disrupt remote administrative access and potentially trigger failover procedures that may introduce latency or temporary service interruptions for dependent applications. While the primary manifestation is system instability leading to unavailability, the underlying memory corruption nature of buffer overflows inherently carries the risk of arbitrary code execution if an attacker can precisely control the overwritten data to manipulate return addresses or function pointers, although exploitation complexity varies based on specific compiler protections and architecture specifics inherent to NonStop environments.
From a vulnerability classification perspective, this issue aligns with CWE-120, which denotes Buffer Copy without Checking Size of Input, highlighting the fundamental programming error where input validation is neglected during memory operations. Furthermore, in the context of attack vectors, this flaw facilitates exploitation techniques categorized under MITRE ATT&CK Tactic TA0004 (Privilege Escalation) or TA0005 (Defense Evasion), specifically relating to process injection or local privilege escalation if the TELSERV service runs with elevated privileges. It also relates to availability attacks as defined in various threat models, where resource exhaustion is achieved through application crashes rather than traditional volumetric flooding.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on both immediate remediation and long-term architectural hardening. The most effective solution is the immediate deployment of vendor-provided patches or service packs that address the input validation logic within TELSERV, ensuring all incoming data streams are strictly bounded against allocated buffer limits before processing. In environments where patching cannot be applied immediately due to operational constraints, network-level controls such as firewall rules should be configured to restrict access to Telnet ports exclusively from trusted management subnets, thereby reducing the attack surface exposed to potential external actors. Additionally, enabling advanced memory protection features like Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR), if supported by the specific NonStop hardware and OS version, can significantly increase the difficulty of successful exploitation even if a buffer overflow is triggered. Regular vulnerability scanning focused on network services and continuous monitoring for anomalous process terminations or memory usage spikes in TELSERV processes are also recommended to detect potential probing attempts early.