Cisco has raised a alarm about denial of services vulnerability that may allow remote unauthenticated attacker to cause an affected device to reload. Only IOS XR and IOS XE are not affected. According to Cisco no other products are currently known to be affected. So a best is to save your downtime by fixing the issues with the help of patches. Being its friendly nature make CISCO more popular. See the list given below:-
Vulnerable devices are running an affected version of Cisco IOS Software, and are configured for any of the following:
1. A specific TCP window size
2. TCP path MTU discovery (PMTUD)
3. Stateful Network Address Translation (SNAT) with TCP as the transport protocol
For detailed information refer this link.