CVE-2021-36368An issue was discovered in OpenSSH before 8.9. If a client is using public-key authentication with agent forwarding but without…
- 3.7LowCVSS base score
- 1.7%Exploitation in 30 daysEPSS · top 23% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By mitre
- 8 months later
· 8 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Low3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Modified | 3.1 | Low3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 1.7% · top 23% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 3.7.
Affected products
n/a
- affected n/a
References
References5
- https://www.openssh.com/security.html (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/openssh/openssh-portable/pull/258 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mindrot.org/show_bug.cgi?id=3316 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://docs.ssh-mitm.at/trivialauth.html (opens in a new tab)x_refsource_MISCx_transferred
- https://security-tracker.debian.org/tracker/CVE-2021-36368 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-22988 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-36368)Record last updated .