Analysis of information sources in references of the Wikipedia article "OpenBSD security features" in English language version.
Removed files: libexec/telnetd
Integration of the ProPolice stack protection technology [...] into the system compiler.
ProPolice stack protection has been enabled in the kernel as well.
Support for the NX (No-eXecute) bit on i386, resulting in much better W^X enforcement in userland for hardware that has this feature.
gcc comes with the 'ProPolice' stack protection extension, which is enabled by default.