CVE-2021-36368

LOW
3.7
CVSS Score
Published: March 12, 2022 at 11:24 PM UTC
Updated: June 17, 2026 at 03:58 AM UTC
2 products affected across 2 vendorsDebian LinuxOpenSSH

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Severity
LOW3.7
Exploit prediction
EPSS 2%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 8.9
Affected range stops below 8.9, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (5)

x_refsource_CONFIRMIssue TrackingThird Party Advisory
https://bugzilla.mindrot.org/show_bug.cgi?id=3316
x_refsource_MISCThird Party Advisory
https://docs.ssh-mitm.at/trivialauth.html
x_refsource_MISCPatchThird Party Advisory
https://github.com/openssh/openssh-portable/pull/258
x_refsource_MISCVendor Advisory
https://www.openssh.com/security.html

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.7LOWCISA-ADP
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-287

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