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Vulnerabilities

Vulnerability · CVE-2021-36368

An issue was discovered in OpenSSH before 8.9.

Published Mar 13, 2022 · catalog updated Jun 17, 2026 · An issue was discovered

Last checked Nov 4, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-36368. EPSS is 1.68%. Act only if a listed version of An issue was discovered is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (An issue was discovered).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Low3.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.68%
Remediation
Version ranges on file
Affected products
cpe debian/debian linux · cpe openbsd/openssh

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux10.0
  • cpe debian/debian linux11.0
  • cpe debian/debian linux9.0
  • cpe openbsd/openssh< 8.9

How to fix CVE-2021-36368

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-36368. EPSS is 1.68%. Act only if a listed version of An issue was discovered is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 10.0; debian/debian linux 11.0; debian/debian linux 9.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication. EPSS 1.68%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

OpenSSH security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 13, 2022 · Monitored products — critical

    Detected

    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

  2. Jun 17, 2026 · Monitored products — critical

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2021-36368

    Official CVE identifier

    cve.org
  • Monitored products — criticalVendor advisoryCVE-2021-36368

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 4, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — criticalNov 4, 2026