Index: boost/locale/utf.hpp
===================================================================
--- boost/locale/utf.hpp	(revision 81589)
+++ boost/locale/utf.hpp	(revision 81590)
@@ -219,16 +219,22 @@
                 if(BOOST_LOCALE_UNLIKELY(p==e))
                     return incomplete;
                 tmp = *p++;
+                if (!is_trail(tmp))
+                    return illegal;
                 c = (c << 6) | ( tmp & 0x3F);
             case 2:
                 if(BOOST_LOCALE_UNLIKELY(p==e))
                     return incomplete;
                 tmp = *p++;
+                if (!is_trail(tmp))
+                    return illegal;
                 c = (c << 6) | ( tmp & 0x3F);
             case 1:
                 if(BOOST_LOCALE_UNLIKELY(p==e))
                     return incomplete;
                 tmp = *p++;
+                if (!is_trail(tmp))
+                    return illegal;
                 c = (c << 6) | ( tmp & 0x3F);
             }
 
Index: libs/locale/test/test_codepage_converter.cpp
===================================================================
--- libs/locale/test/test_codepage_converter.cpp	(revision 81589)
+++ libs/locale/test/test_codepage_converter.cpp	(revision 81590)
@@ -140,6 +140,20 @@
         TEST_TO("\xf8\x90\x80\x80\x80",illegal);  // 400 0000
         TEST_TO("\xfd\xbf\xbf\xbf\xbf\xbf",illegal);  // 7fff ffff
 
+        std::cout << "-- Invalid trail" << std::endl;
+        TEST_TO("\xC2\x7F",illegal);
+        TEST_TO("\xdf\x7F",illegal);
+        TEST_TO("\xe0\x7F\x80",illegal);
+        TEST_TO("\xef\xbf\x7F",illegal);
+        TEST_TO("\xe0\x7F\x80",illegal);
+        TEST_TO("\xef\xbf\x7F",illegal);
+        TEST_TO("\xf0\x7F\x80\x80",illegal);
+        TEST_TO("\xf4\x7f\xbf\xbf",illegal);
+        TEST_TO("\xf0\x90\x7F\x80",illegal);
+        TEST_TO("\xf4\x8f\x7F\xbf",illegal);
+        TEST_TO("\xf0\x90\x80\x7F",illegal);
+        TEST_TO("\xf4\x8f\xbf\x7F",illegal);
+
         std::cout << "-- Invalid length" << std::endl;
 
         /// Test that this actually works