CVE-2020-37165 in AbsoluteTelnet
Summary
by MITRE • 02/07/2026
AbsoluteTelnet 11.12 contains a denial of service vulnerability that allows local attackers to crash the application by supplying an oversized license name. Attackers can generate a 2500-character payload and paste it into the license name field to trigger an application crash.
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Analysis
by VulDB Data Team • 02/19/2026
The vulnerability identified as CVE-2020-37165 affects AbsoluteTelnet version 11.12 and represents a denial of service condition that can be exploited by local attackers. This flaw manifests when the application processes a license name field containing an excessively large payload, specifically a 2500-character string that triggers an application crash. The vulnerability resides in the input validation mechanisms of the licensing component, where the software fails to properly handle or sanitize user-supplied data before processing it within the application context.
From a technical perspective, this vulnerability demonstrates a classic buffer overflow or input length validation issue that falls under the CWE-122 category of buffer overflow vulnerabilities. The flaw occurs because the application does not implement proper bounds checking on the license name field, allowing attackers to exceed the allocated memory space for license information storage. This type of vulnerability typically stems from insufficient input sanitization and validation practices, where the software assumes that user inputs will remain within expected parameters without adequate boundary checks.
The operational impact of this vulnerability is significant for local attackers who possess the ability to interact with the application's licensing interface. Since the exploit requires only local access to paste a large payload into the license name field, it represents a relatively low-barrier attack vector that can disrupt service availability. The application crash caused by this vulnerability effectively renders the telnet client unusable until manual restart or system reboot occurs, creating operational downtime that can affect network administration tasks and remote access operations.
From an attacker's perspective, this vulnerability aligns with the ATT&CK technique T1499.004 which involves network denial of service attacks through resource exhaustion or application crashes. The local privilege requirement makes this attack vector particularly concerning for environments where unauthorized local access might be gained through social engineering or compromised user accounts. The vulnerability also relates to the broader category of application-level denial of service attacks that can be used to disrupt business operations and compromise system availability.
Mitigation strategies should focus on implementing proper input validation and length restrictions on all user-supplied data fields, particularly those used for licensing or configuration purposes. The software should enforce maximum character limits on license name fields and implement robust error handling mechanisms that prevent malformed inputs from causing application crashes. Additionally, regular security updates and patches should be applied to address such vulnerabilities before they can be exploited. Organizations should also consider implementing monitoring systems to detect unusual application behavior patterns that might indicate denial of service attacks. The vulnerability highlights the importance of defensive programming practices including input sanitization, proper memory management, and comprehensive error handling to prevent similar issues in network administration tools.