I managed to trigger a kernel panic from one of the core built-in iOS applications when I was playing around with my iPhone 6+ (running 8.1.3 non-jailbroken).
It was possible to replicate the crash after several attempts and I have found the method to replicate the crash on demand. Using that method, I was also able to replicate the crash on my iPhone 5S (running 8.1.3 non-jailbroken).
I was unable to replicate the crash on one iPhone 5 (running 8.1.2 non-jailbroken) and one iPhone 6 (running 8.1.2 non-jailbroken). This could be an issue with iOS 8.1.3 only. I have reported the bug to Apple Security.
Update: Tested on iOS 8.2 and the issue was still present.
[snip] ... Debugger message: panic OS version: 12B466 Kernel version: Darwin Kernel Version 14.0.0: Mon Jan 12 21:30:05 PST 2015; root:xnu2783.3.26~3/RELEASE_ARM64_T7000 iBoot version: iBoot2261.3.33 secure boot?: YES Paniclog version: 3 Kernel slide: 0x0000000004600000 Kernel text base: 0xffffff8006602000 Epoch Time: sec usec Boot : 0x54face5c 0x00000000 Sleep : 0x00000000 0x00000000 Wake : 0x00000000 0x00000000 Calendar: 0x54fad0e2 0x00008ad6 Panicked task 0xffffff808841fb20: 25645 pages, 182 threads: pid 0: kernel_task panicked thread: 0xffffff80886a21a0, backtrace: 0xffffff800312bab0 lr: 0xffffff80066db3c8 fp: 0xffffff800312bb10 lr: 0xffffff8006620f20 fp: 0xffffff800312bb70 lr: 0xffffff8006915e94 fp: 0xffffff800312bca0 lr: 0xffffff80066d83a0 fp: 0x0000000000000000 [snip] ...