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.
Exploitability
AV:NAC:HAu:NImpact
C:PI:PA:P5.1/AV:N/AC:H/Au:N/C:P/I:P/A:P