rp-pppoe PPPoE client allows remote attackers to cause a denial of service via the Clamp MSS option and a TCP packet with a zero-length TCP option.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5727
http://www.securityfocus.com/bid/2098
http://www.linux-mandrake.com/en/security/MDKSA-2000-084.php3
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000357
http://archives.neohapsis.com/archives/bugtraq/2000-12/0134.html