The proc_open function in ext/standard/proc_open.c in PHP before
5.2.11 and 5.3.x before 5.3.1 does not enforce the (1)
safe_mode_allowed_env_vars and (2) safe_mode_protected_env_vars
directives, which allows context-dependent attackers to execute
programs with an arbitrary environment via the env parameter, as
demonstrated by a crafted value of the LD_LIBRARY_PATH environment
variable.