Auth bypass in Openbsd Openssh
CVE-2021-36368
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.
Vulnerability class: Broken Authentication
EPSS: 0.017 (74.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Openbsd Openssh
- Debian Debian_linux — versions 9.0, 10.0, 11.0
- N/a — versions n/a
Weakness classification (CWE)
Public proof-of-concept exploits
References
- cve@mitre.org (x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (Patch, Third Party Advisory, x_refsource_MISC)
- cve@mitre.org (x_refsource_CONFIRM, Third Party Advisory, Issue Tracking)
- cve@mitre.org (Third Party Advisory, x_refsource_MISC)
- cve@mitre.org (Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-36368?
- CVE-2021-36368 is a low-severity vulnerability in Openbsd Openssh, classified under Improper Authentication. CVSS score: 3.7/10. Published 2022-03-13.
- How severe is CVE-2021-36368?
- Low severity. CVSS v3 base score is 3.7 out of 10.
- Is CVE-2021-36368 known to be exploited?
- 22 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.