CVE-2020-37166 AbsoluteTelnet 11.12 - 'SSH2/username' Denial of Service

Medium 6.9 Published 6 Feb 2026 Updated 1 Oct 2026

Local attackers can crash AbsoluteTelnet by overwriting the SSH2 username field with a large buffer, causing application termination.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2020-37166?

CVE-2020-37166 is a medium-severity denial of service vulnerability in Celestial Software AbsoluteTelnet, published on 6 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-120

Which versions are affected by CVE-2020-37166?

It affects 1 product.

Products include Celestialsoftware Absolutetelnet.

How do I fix CVE-2020-37166?

No fix has been published for CVE-2020-37166 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-37166 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-37166 exists.

Sources

Also known as GHSA-vp6j-grx7-8jmx.