Several patches are available to fix kernel errata. Please refer to http://www.openbsd.org/errata59.html and errata58.html for details and patches.
Patches for 5.9 include: 013: RELIABILITY FIX: July 14, 2016 All architectures Splicing sockets in a loop could cause a kernel spin. 014: RELIABILITY FIX: July 14, 2016 All architectures Multiple processes exiting with a fd-passing control message on a shared socket could crash the system. 015: RELIABILITY FIX: July 14, 2016 All architectures ufs_readdir failed to limit size of memory allocation, leading to panics. 016: SECURITY FIX: July 14, 2016 All architectures The mmap extension __MAP_NOFAULT could overcommit resources and crash the system. 017: RELIABILITY FIX: July 14, 2016 All architectures A race occuring in the unlocked ARP input path can lead to a kernel NULL dereference. 018: RELIABILITY FIX: July 14, 2016 All architectures Tick counting overflows could cause a kernel crash. 019: RELIABILITY FIX: July 14, 2016 All architectures Invalid file descriptor use with kevent(2) could lead to a kernel crash. 020: RELIABILITY FIX: July 14, 2016 All architectures Unchecked parameters and integer overflows in the amap allocation routines could cause malloc(9) to either not allocate enough memory, leading to memory corruption, or to trigger a "malloc: allocation too large" panic.
