CVE-2021-36368: Debian Linux

Low severity, CVSS 3.7. EPSS: 1.7% chance of exploitation in the next 30 days.

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.

Affected products

• Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
• OpenBSD OpenSSH: before 8.9 (fixed in 8.9)

Published 2022-03-13. Last modified 2026-06-17.