diff -up pam/modules/pam_env/pam_env.c.nouserenv pam/modules/pam_env/pam_env.c
--- pam/modules/pam_env/pam_env.c.nouserenv	2010-10-20 09:59:30.000000000 +0200
+++ pam/modules/pam_env/pam_env.c	2010-11-01 14:42:01.000000000 +0100
@@ -10,7 +10,7 @@
 #define DEFAULT_READ_ENVFILE    1
 
 #define DEFAULT_USER_ENVFILE    ".pam_environment"
-#define DEFAULT_USER_READ_ENVFILE 1
+#define DEFAULT_USER_READ_ENVFILE 0
 
 #include "config.h"
 
diff -up pam/modules/pam_env/pam_env.8.xml.nouserenv pam/modules/pam_env/pam_env.8.xml
--- pam/modules/pam_env/pam_env.8.xml.nouserenv	2010-10-20 09:59:30.000000000 +0200
+++ pam/modules/pam_env/pam_env.8.xml	2010-11-01 14:42:01.000000000 +0100
@@ -147,7 +147,10 @@
         <listitem>
           <para>
             Turns on or off the reading of the user specific environment
-            file. 0 is off, 1 is on. By default this option is on.
+            file. 0 is off, 1 is on. By default this option is off as user
+            supplied environment variables in the PAM environment could affect
+            behavior of subsequent modules in the stack without the consent
+            of the system administrator.
           </para>
         </listitem>
       </varlistentry>