Bug ID 1920341: SSH Public Key authentication allows RSA and not ECDSA in ccmode

Last Modified: Jun 28, 2025

Affected Product(s):
BIG-IP TMOS(all modules)

Known Affected Versions:
17.5.0

Fixed In:
17.5.1

Opened: Apr 03, 2025

Severity: 3-Major

Symptoms

When a device is in common criteria mode, you cannot use ecdsa-sha2-nistp256 or ecdsa-sha2-nistp384 for SSH public key authentication. Additionally, you can use rsa key which you should not be able to according to common criteria guidelines.

Impact

You cannot ssh with ECDSA but can with RSA key

Conditions

-- Common Criteria mode is enabled

Workaround

Workaround is in file /config/ssh/sshd_config, on line 34 replace: HostKey /config/ssh/ssh_host_rsa_key with: HostKey /config/ssh/ssh_host_ecdsa_key HostKey /config/ssh/ssh_host_ecdsa_p384_key Note that this workaround must be applied after each reboot in ccmode, since the sshd_config file will revert after reboot.

Fix Information

SSH public key authentication works as expected in ccmode.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips