Published: 02 August 2015
The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.
Launchpad, Ubuntu, Debian
|Ubuntu 14.04 ESM (Trusty Tahr)||
Only affects systems with KbdInteractiveAuthentication set to 'yes'. By default, that option is set to 'no' in Ubuntu.