Vulnerability 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.
CVSS Score
LOW
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Openbsd | Openssh | < 8.9 |
| Debian | Debian Linux | 9.0 |
Related Weaknesses (CWE)
References
- https://bugzilla.mindrot.org/show_bug.cgi?id=3316Issue TrackingThird Party Advisory
- https://docs.ssh-mitm.at/trivialauth.htmlThird Party Advisory
- https://github.com/openssh/openssh-portable/pull/258PatchThird Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2021-36368Third Party Advisory
- https://www.openssh.com/security.htmlVendor Advisory
- https://bugzilla.mindrot.org/show_bug.cgi?id=3316Issue TrackingThird Party Advisory
- https://docs.ssh-mitm.at/trivialauth.htmlThird Party Advisory
- https://github.com/openssh/openssh-portable/pull/258PatchThird Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2021-36368Third Party Advisory
- https://www.openssh.com/security.htmlVendor Advisory
FAQ
What is CVE-2021-36368?
CVE-2021-36368 is a vulnerability with a CVSS score of 3.7 (LOW). 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 ...
How severe is CVE-2021-36368?
CVE-2021-36368 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-36368?
Check the references section above for vendor advisories and patch information. Affected products include: Openbsd Openssh, Debian Debian Linux.