PaX is a patch for the Linux kernel that implements least privilege protections for memory pages. The least-privilege approach allows computer programs to do only what they have to do in order to be able to execute properly, and nothing more.PaX was first released in 2000. PaX flags data memory as non-executable, program memory as non-writable and randomly arranges the program memory.he major feature of PaX is the executable space protection it offers. These protections take advantage of the NX bit on certain processors to prevent the execution of arbitrary code.