diff -uw ruby-2.1.1/ext/psych/yaml/config.h ruby-2.1.2/ext/psych/yaml/config.h
--- ruby-2.1.1/ext/psych/yaml/config.h	2014-02-24 05:24:15.000000000 +0100
+++ ruby-2.1.2/ext/psych/yaml/config.h	2014-05-04 17:45:33.000000000 +0200
@@ -1,11 +1,10 @@
-
 #define PACKAGE_NAME "yaml"
 #define PACKAGE_TARNAME "yaml"
-#define PACKAGE_VERSION "0.1.5"
-#define PACKAGE_STRING "yaml 0.1.5"
+#define PACKAGE_VERSION "0.1.6"
+#define PACKAGE_STRING "yaml 0.1.6"
 #define PACKAGE_BUGREPORT "http://pyyaml.org/newticket?component libyaml"
 #define PACKAGE_URL ""
 #define YAML_VERSION_MAJOR 0
 #define YAML_VERSION_MINOR 1
-#define YAML_VERSION_PATCH 5
-#define YAML_VERSION_STRING "0.1.5"
+#define YAML_VERSION_PATCH 6
+#define YAML_VERSION_STRING "0.1.6"
diff -uw ruby-2.1.1/ext/psych/yaml/scanner.c ruby-2.1.2/ext/psych/yaml/scanner.c
--- ruby-2.1.1/ext/psych/yaml/scanner.c	2014-02-24 05:24:15.000000000 +0100
+++ ruby-2.1.2/ext/psych/yaml/scanner.c	2014-05-04 17:45:33.000000000 +0200
@@ -2629,6 +2629,9 @@
         /* Check if it is a URI-escape sequence. */
 
         if (CHECK(parser->buffer, '%')) {
+            if (!STRING_EXTEND(parser, string))
+                goto error;
+
             if (!yaml_parser_scan_uri_escapes(parser,
                         directive, start_mark, &string)) goto error;
         }
diff -uw ruby-2.1.1/ext/psych/yaml/yaml_private.h ruby-2.1.2/ext/psych/yaml/yaml_private.h
--- ruby-2.1.1/ext/psych/yaml/yaml_private.h	2014-02-24 05:24:15.000000000 +0100
+++ ruby-2.1.2/ext/psych/yaml/yaml_private.h	2014-05-04 17:45:33.000000000 +0200
@@ -146,9 +146,12 @@
      (string).start = (string).pointer = (string).end = 0)
 
 #define STRING_EXTEND(context,string)                                           \
-    (((string).pointer+5 < (string).end)                                        \
+    ((((string).pointer+5 < (string).end)                                       \
         || yaml_string_extend(&(string).start,                                  \
-            &(string).pointer, &(string).end))
+            &(string).pointer, &(string).end)) ?                                \
+         1 :                                                                    \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
 
 #define CLEAR(context,string)                                                   \
     ((string).pointer = (string).start,                                         \