--- a/src/java.security.jgss/share/classes/sun/security/jgss/spnego/SpNegoContext.java	Wed Aug 22 11:10:45 2018 +0800
+++ b/src/java.security.jgss/share/classes/sun/security/jgss/spnego/SpNegoContext.java	Tue Aug 21 20:19:46 2018 -0700
@@ -583,7 +583,8 @@
                     }
                 } else {
                     negoResult = SpNegoToken.NegoResult.REJECT;
-                    state = STATE_DONE;
+                    state = STATE_DELETED;
+                    throw new GSSException(GSSException.FAILURE);
                 }
 
                 if (DEBUG) {
@@ -642,7 +643,8 @@
                     }
                 } else {
                     negoResult = SpNegoToken.NegoResult.REJECT;
-                    state = STATE_DONE;
+                    state = STATE_DELETED;
+                    throw new GSSException(GSSException.FAILURE);
                 }
 
                 // generate SPNEGO token

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/sun/security/krb5/auto/SpnegoUnknownMech.java	Tue Aug 21 20:19:46 2018 -0700
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8186186
+ * @library /test/lib
+ * @compile -XDignore.symbol.file SpnegoRejected.java
+ * @run main jdk.test.lib.FileInstaller TestHosts TestHosts
+ * @run main/othervm/fail -Djdk.net.hosts.file=TestHosts SpnegoRejected
+ */
+
+import sun.security.jgss.GSSUtil;
+
+public class SpnegoRejected {
+
+    public static void main(String[] args) throws Exception {
+
+        new OneKDC(null).writeJAASConf();
+
+        Context c, s;
+        c = Context.fromJAAS("client");
+        s = Context.fromJAAS("server");
+
+        c.startAsClient(OneKDC.SERVER, GSSUtil.GSS_SPNEGO_MECH_OID);
+        s.startAsServer(GSSUtil.GSS_SPNEGO_MECH_OID);
+
+        byte[] init = c.take(new byte[0]);
+        // Modify the krb5 mech OID inside NegTokenInit to something else
+        init[0x20] = 10;
+        s.take(init);
+
+        s.dispose();
+        c.dispose();
+    }
+}