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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssh | 1:8.9p1-1 | — |
| Debian 13 | openssh | 1:8.9p1-1 | — |
| Debian 12 | openssh | 1:8.9p1-1 | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | openssh | 8.9_p1-r0 | — |
| Alpine v3.23 | openssh | 8.9_p1-r0 | — |
| Alpine v3.22 | openssh | 8.9_p1-r0 | — |
| Alpine v3.21 | openssh | 8.9_p1-r0 | — |
| Alpine v3.20 | openssh | 8.9_p1-r0 | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | openssh | 8.9_p1-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | openssh | 8.9p1-1 | — |
Advisories 4
- SCA-2025-0011 Vulnerabilities affecting Endress+Hauser SSG-E210GC SICK PSIRT · Oct 2, 2025
- WID-SEC-2025-2096 NetApp ActiveIQ Unified Manager: Schwachstelle ermöglicht Offenlegung von Informationen BSI CERT-Bund (WID) · Sep 21, 2025
- SCA-2025-0009 Vulnerabilities affecting SICK TDC-E210GC SICK PSIRT · Aug 1, 2025
- WID-SEC-2024-1082 Juniper JUNOS: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 9, 2024