Buffer Overflows such as this one require an advanced skillset, and time and knowledge to exploit. In addition, the exploit must be specific to the version that is targeted (as noted by Google Mandiant).
The recommendation is to fix according to your usual critical patching schedule, but prioritise over other criticals as this vulnerability has been added to the KEV list. That said, due to the complexities with this vulnerability class, we don't expect widespread exploitation.
Patching information has been released by Ivanti. However, the recommendation to use the ICT scanner by Ivanti appears to be flawed as pointed out by Google Mandiant. To help with detecting compromises, they have released YARA rules for this vulnerability.