This indicates an attack attempt to exploit a Denial of Service vulnerability in Cisco IOS with Smart Install Client feature enabled.
The vulnerability is caused by an error in the vulnerable software when handling image list parameters. A remote attacker may be able to exploit this to cause a denial of service condition, via a crafted Smart Install packet.
Cisco IOS 12.2
Cisco IOS 15.0
Cisco IOS 15.2
Cisco IOS XE 3.2 through 3.7
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.