QID 38900

Date Published: 2023-07-19

QID 38900: OpenSSH Public-Key Authentication Vulnerability

OpenSSH (OpenBSD Secure Shell) is a set of computer programs providing encrypted communication sessions over a computer network using the SSH protocol.

OpenSSH contains the following vulnerabilities:
CVE-2021-36368: 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.

Affected Versions:
OpenSSH versions prior to 8.9

QID Detection Logic:
This unauthenticated detection works by reviewing the version of the OpenSSH service.

Successful exploitation allows a remote attacker silently modify the server to support the None authentication option when a client is using public-key authentication with agent forwarding but without -oLogLevel=verbose.

  • CVSS V3 rated as Medium - 3.7 severity.
  • CVSS V2 rated as Low - 2.6 severity.
    • Solution
    Customers are advised to upgrade to OpenSSH 8.9 or later to remediate these vulnerabilities.
    Vendor References

    CVEs related to QID 38900

    CVE-2021-36368 |
    Software Advisories
    Advisory ID Software Component Link
    OpenSSH 8.9 or later URL Logo www.openssh.com/
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