Oracle 10g R2 and possibly other versions allows remote attackers to trigger internal errors, and possibly have other impacts, via an "alter session set events" command with invalid arguments. NOTE: this issue was originally disputed by a third party, but the dispute was retracted. NOTE: this issue was called an "integer overflow" in the original source, but this might be incorrect.
http://www.securityfocus.com/archive/1/441477/100/0/threaded
http://www.securityfocus.com/archive/1/441345/100/0/threaded
http://securityreason.com/securityalert/2328
http://lists.grok.org.uk/pipermail/full-disclosure/2006-July/048292.html