Backport rev 55450:
SF bug #1721309: Clear data so random memory does not get freed.
diff --git a/Modules/_bsddb.c b/Modules/_bsddb.c
index 9622c90..f064878 100644
--- a/Modules/_bsddb.c
+++ b/Modules/_bsddb.c
@@ -1713,6 +1713,7 @@
         return NULL;
     }
 
+    CLEAR_DBT(data);
     flags |= DB_GET_BOTH;
 
     if (CHECK_DBFLAG(self, DB_THREAD)) {