This indicates an attempt to exploit a Heap Based Buffer Overflow Vulnerability in Libtiff.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted TIFF file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted TIFF file.
libtiff 4.0.9 and prior
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the latest update from the vendor.