IBM OS/400 (aka i5/OS) V4R2M0 through V5R3M0 on iSeries machines sends responses to TCP SYN-FIN packets, which allows remote attackers to obtain system information and possibly bypass firewall rules.

Unknown vulnerability in Incoming Remote Command (iSeries Access for Windows Remote Command service) in IBM OS/400 R510, R520, and R530 allows attackers to cause a denial of service (IRC shutdown) via certain inputs.