diff -up cups-1.7.0/cups/usersys.c.str4327 cups-1.7.0/cups/usersys.c

--- cups-1.7.0/cups/usersys.c.str4327	2013-07-10 15:08:39.000000000 +0100

+++ cups-1.7.0/cups/usersys.c	2014-01-08 16:30:40.443026913 +0000

@@ -875,7 +875,25 @@ _cupsSetDefaults(void)

   cups_expiredcerts   = getenv("CUPS_EXPIREDCERTS");

   if ((cups_user = getenv("CUPS_USER")) == NULL)

-    cups_user = getenv("USER");

+  {

+   /*

+    * Try the USER environment variable...

+    */

+

+    if ((cups_user = getenv("USER")) != NULL)

+    {

+     /*

+      * Validate USER matches the current UID, otherwise don't allow it to

+      * override things...  This makes sure that printing after doing su or

+      * sudo records the correct username.

+      */

+

+      struct passwd	*pw;		/* Account information */

+

+      if ((pw = getpwnam(cups_user)) == NULL || pw->pw_uid != getuid())

+        cups_user = NULL;

+    }

+  }

  /*

   * Then, if needed, read the ~/.cups/client.conf or /etc/cups/client.conf