AVG Internet Security 2015 allocates memory with Read, Write, Execute (RWX) permissions at predictable addresses when protecting user-mode processes, which allows attackers to bypass the DEP and ASLR protection mechanisms via unspecified vectors.
The TDI driver (avgtdix.sys) in AVG Internet Security before 2013.3495 Hot Fix 18 and 2015.x before 2015.5315 and Protection before 2015.5315 allows local users to write to arbitrary memory locations, and consequently gain privileges, via a crafted 0x830020f8 IOCTL call.