CVE-2020-37166 in AbsoluteTelnet
Summary
by MITRE • 02/07/2026
AbsoluteTelnet 11.12 contains a denial of service vulnerability in the SSH2 username input field that allows local attackers to crash the application. Attackers can overwrite the username field with a 1000-byte buffer, causing the application to become unresponsive and terminate.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/19/2026
The vulnerability identified as CVE-2020-37166 affects AbsoluteTelnet version 11.12 and represents a classic buffer overflow condition within the SSH2 username input handling mechanism. This flaw exists in the application's input validation processes where the system fails to properly sanitize or limit the length of user-provided data during authentication attempts. The vulnerability specifically targets the username field within the SSH2 protocol implementation, creating a scenario where malformed input can trigger unexpected application behavior.
The technical exploitation of this vulnerability requires minimal prerequisites as it targets a local attack vector where an authenticated user or malicious actor with access to the system can craft a specially formatted input string. When a 1000-byte buffer is entered into the username field, the application's memory management routines fail to handle this excessive input properly, leading to memory corruption that ultimately results in application termination. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations.
The operational impact of this denial of service condition extends beyond simple application instability as it can disrupt legitimate user sessions and create availability issues for network services. Local attackers can leverage this vulnerability to repeatedly crash the AbsoluteTelnet service, potentially causing service interruption for authorized users who depend on secure remote access capabilities. The vulnerability's local nature means that it does not require network exposure, making it particularly concerning for systems where local privilege escalation might be possible, as it could serve as a stepping stone for further compromise.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, though the local nature of this specific flaw makes it more aligned with privilege escalation and service disruption tactics. The vulnerability demonstrates poor input validation practices that violate fundamental security principles and could potentially be exploited in combination with other local vulnerabilities to achieve more significant impacts. Organizations should consider this vulnerability as part of a broader security assessment that includes review of input handling mechanisms and memory management practices within their remote access solutions.
Mitigation strategies for CVE-2020-37166 should focus on immediate patching of the AbsoluteTelnet application to the latest version that addresses this buffer overflow condition. System administrators should implement input length restrictions at the application level to prevent excessively long strings from being processed, while also monitoring for unusual authentication patterns that might indicate exploitation attempts. Network segmentation and access controls should be reviewed to limit local access to systems running AbsoluteTelnet, reducing the attack surface for local privilege escalation scenarios. Additionally, organizations should conduct regular vulnerability assessments of their remote access infrastructure to identify and remediate similar input validation weaknesses that could lead to more severe security incidents.