This indicates an attack attempt against a Denial Of Service vulnerability in rsyslog.
The vulnerability is caused by an integer overflow error when the vulnerable software handles maliciously crafted log message data. A remote attacker may be able to exploit this to cause denial of service conditions in the affected machine via crafted packets.
Infodrom Oldenburg sysklogd prior to 1.5
rsyslog rsyslog prior to 7.6.7
rsyslog rsyslog prior to 8.4.2
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.