CVE-2021-47765 AbsoluteTelnet 11.24 - 'Username' Denial of Service (PoC)

Medium 6.7 Published 15 Jan 2026 Updated 1 Oct 2026

Local attackers can crash the AbsoluteTelnet application by inserting excessive characters into username or email fields, causing a denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2021-47765?

CVE-2021-47765 is a medium-severity denial of service vulnerability in Celestialsoftware AbsoluteTelnet, published on 15 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

AbsoluteTelnet 11.24 contains a denial of service vulnerability that allows local attackers to crash the application by manipulating username and error report fields. Attackers can trigger the crash by inserting 1000 characters into the username or email address fields, causing the application to become unresponsive.

Weakness: CWE-787

Which versions are affected by CVE-2021-47765?

It affects 1 product.

Products include Celestialsoftware Absolutetelnet.

How do I fix CVE-2021-47765?

No fix has been published for CVE-2021-47765 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-2021-47765 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47765 exists.

Sources

Also known as GHSA-chp4-5883-3f2x.