The source for Cisco's IOS has been in rogue hands for quite some time. The Chinese network equipment manufacturer Huawei was caught selling routers in the run

The source for Cisco's IOS has been in rogue hands for quite some time. The Chinese network equipment manufacturer Huawei was caught selling routers in the running IOS with only cursory changes back in 2003. Identical CLI, identical features, identical bugs. I think we must assume that the source code for most major products is available on the black market.