The arch_pick_mmap_layout function in arch/x86/mm/mmap.c in the Linux kernel through 4.5.2 does not properly randomize the legacy base address, which makes it easier for local users to defeat the intended restrictions on the ADDR_NO_RANDOMIZE flag, and bypass the ASLR protection mechanism for a setuid or setgid program, by disabling stack-consumption resource limits.
The PTR_MANGLE implementation in the GNU C Library (aka glibc or libc6) 2.4, 2.17, and earlier, and Embedded GLIBC (EGLIBC) does not initialize the random value for the pointer guard, which makes it easier for context-dependent attackers to control execution flow by leveraging a buffer-overflow vulnerability in an application and using the known zero value pointer guard to calculate a pointer address.