This indicates an attack attempt against a Buffer Over Read vulnerability in the receive_xattr function of rsync.
The vulnerability is due to a lack of bounds checks when the vulnerable software handles a maliciously crafted packet. A remote attacker may to able to exploit this to cause a denial of service condition on the affected system.
rsync Project rsync 3.1.2
rsync Project rsync 3.1.3-development
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.