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.
References (5)
Core 5
Core References
Vendor Advisory x_refsource_misc
https://www.openssh.com/security.html
Patch, Third Party Advisory x_refsource_misc
https://github.com/openssh/openssh-portable/pull/258
Issue Tracking, Third Party Advisory x_refsource_confirm
https://bugzilla.mindrot.org/show_bug.cgi?id=3316
Third Party Advisory x_refsource_misc
https://docs.ssh-mitm.at/trivialauth.html
Third Party Advisory x_refsource_misc
https://security-tracker.debian.org/tracker/CVE-2021-36368
Scores
CVSS v3
3.7
EPSS
0.0043
EPSS Percentile
62.8%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Details
CWE
CWE-287
Status
published
Products (4)
debian/debian_linux
9.0
debian/debian_linux
10.0
debian/debian_linux
11.0
openbsd/openssh
< 8.9
Published
Mar 13, 2022
Tracked Since
Feb 18, 2026