OpenSSH before 2.9.9, while using keypairs and multiple keys of different types in the ~/.ssh/authorized_keys2 file, may not properly handle the "from" option associated with a key, which could allow remote attackers to login from unauthorized IP addresses.
https://exchange.xforce.ibmcloud.com/vulnerabilities/7179
http://www.securityfocus.com/bid/3369
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-081.php
http://www.kb.cert.org/vuls/id/905795
http://www.ciac.org/ciac/bulletins/m-010.shtml
http://rhn.redhat.com/errata/RHSA-2001-114.html
http://marc.info/?l=bugtraq&m=100154541809940&w=2
http://download.immunix.org/ImmunixOS/7.0/updates/IMNX-2001-70-034-01
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000431