Buffer overflow in ftpd 5.4 in 3Com NBX 4.0.17 or ftpd 5.4.2 in 3Com NBX 4.1.4 allows remote attackers to cause a denial of service (crash) via a long CEL command.
https://exchange.xforce.ibmcloud.com/vulnerabilities/10739
http://www.kb.cert.org/vuls/id/317417
http://securitytracker.com/id?1006760
http://securitytracker.com/id?1005732