diff --git a/ChangeLog b/ChangeLog
index 5f2e473f80..2acdf64509 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Sep 13 16:43:36 2006  Yukihiro Matsumoto  <matz@ruby-lang.org>
+ 
+ 	* string.c (rb_str_intern): prohibit interning tainted string.
+ 
 Wed Sep 13 01:14:02 2006  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/optparse.rb (OptionParser#getopts): works with pre-registered
diff --git a/string.c b/string.c
index 094907fe54..332b6186dd 100644
--- a/string.c
+++ b/string.c
@@ -4153,6 +4153,9 @@ rb_str_intern(VALUE s)
     }
     if (strlen(RSTRING_PTR(str)) != RSTRING_LEN(str))
 	rb_raise(rb_eArgError, "symbol string may not contain `\\0'");
+    if (OBJ_TAINTED(str)) {
+	rb_raise(rb_eSecurityError, "Insecure: can't intern tainted string");
+    }
     id = rb_intern(RSTRING_PTR(str));
     return ID2SYM(id);
 }