--- a/src/share/classes/java/net/URLClassLoader.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/java/net/URLClassLoader.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -45,6 +45,7 @@
 import java.security.Permission;
 import java.security.PermissionCollection;
 import sun.misc.Resource;
+import sun.misc.SharedSecrets;
 import sun.misc.URLClassPath;
 import sun.net.www.ParseUtil;
 import sun.security.util.SecurityConstants;
@@ -314,13 +315,13 @@
     protected Package definePackage(String name, Manifest man, URL url)
         throws IllegalArgumentException
     {
-        String path = name.replace('.', '/').concat("/");
         String specTitle = null, specVersion = null, specVendor = null;
         String implTitle = null, implVersion = null, implVendor = null;
         String sealed = null;
         URL sealBase = null;
 
-        Attributes attr = man.getAttributes(path);
+        Attributes attr = SharedSecrets.javaUtilJarAccess()
+                .getTrustedAttributes(man, name.replace('.', '/').concat("/"));
         if (attr != null) {
             specTitle   = attr.getValue(Name.SPECIFICATION_TITLE);
             specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
@@ -364,10 +365,12 @@
     /*
      * Returns true if the specified package name is sealed according to the
      * given manifest.
+     *
+     * @throws SecurityException if the package name is untrusted in the manifest
      */
     private boolean isSealed(String name, Manifest man) {
-        String path = name.replace('.', '/').concat("/");
-        Attributes attr = man.getAttributes(path);
+        Attributes attr = SharedSecrets.javaUtilJarAccess()
+                .getTrustedAttributes(man, name.replace('.', '/').concat("/"));
         String sealed = null;
         if (attr != null) {
             sealed = attr.getValue(Name.SEALED);

--- a/src/share/classes/java/util/jar/JarFile.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/java/util/jar/JarFile.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -177,10 +177,10 @@
             if (manEntry != null) {
                 if (verify) {
                     byte[] b = getBytes(manEntry);
-                    man = new Manifest(new ByteArrayInputStream(b));
                     if (!jvInitialized) {
                         jv = new JarVerifier(b);
                     }
+                    man = new Manifest(jv, new ByteArrayInputStream(b));
                 } else {
                     man = new Manifest(super.getInputStream(manEntry));
                 }

--- a/src/share/classes/java/util/jar/JarVerifier.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/java/util/jar/JarVerifier.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -866,4 +866,24 @@
     static CodeSource getUnsignedCS(URL url) {
         return new VerifierCodeSource(null, url, (java.security.cert.Certificate[]) null);
     }
+
+    /**
+     * Returns whether the name is trusted. Used by
+     * {@link Manifest#getTrustedAttributes(String)}.
+     */
+    boolean isTrustedManifestEntry(String name) {
+        // How many signers? MANIFEST.MF is always verified
+        CodeSigner[] forMan = (CodeSigner[]) verifiedSigners.get(JarFile.MANIFEST_NAME);
+        if (forMan == null) {
+            return true;
+        }
+        // Check sigFileSigners first, because we are mainly dealing with
+        // non-file entries which will stay in sigFileSigners forever.
+        CodeSigner[] forName = (CodeSigner[]) sigFileSigners.get(name);
+        if (forName == null) {
+            forName = (CodeSigner[]) verifiedSigners.get(name);
+        }
+        // Returns trusted if all signers sign the entry
+        return forName != null && forName.length == forMan.length;
+    }
 }

--- a/src/share/classes/java/util/jar/JavaUtilJarAccessImpl.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/java/util/jar/JavaUtilJarAccessImpl.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 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
@@ -60,4 +60,9 @@
     public List getManifestDigests(JarFile jar) {
         return jar.getManifestDigests();
     }
+
+    public Attributes getTrustedAttributes(Manifest man, String name) {
+        return man.getTrustedAttributes(name);
+    }
+
 }

--- a/src/share/classes/java/util/jar/Manifest.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/java/util/jar/Manifest.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 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
@@ -48,15 +48,19 @@
  */
 public class Manifest implements Cloneable {
     // manifest main attributes
-    private Attributes attr = new Attributes();
+    private final Attributes attr = new Attributes();
 
     // manifest entries
-    private Map entries = new HashMap();
+    private final Map<String, Attributes> entries = new HashMap<String, Attributes>();
+
+    // associated JarVerifier, not null when called by JarFile::getManifest.
+    private final JarVerifier jv;
 
     /**
      * Constructs a new, empty Manifest.
      */
     public Manifest() {
+        jv = null;
     }
 
     /**
@@ -66,7 +70,16 @@
      * @throws IOException if an I/O error has occured
      */
     public Manifest(InputStream is) throws IOException {
+        this(null, is);
+    }
+
+    /**
+     * Constructs a new Manifest from the specified input stream
+     * and associates it with a JarVerifier.
+     */
+    Manifest(JarVerifier jv, InputStream is) throws IOException {
         read(is);
+        this.jv = jv;
     }
 
     /**
@@ -77,6 +90,7 @@
     public Manifest(Manifest man) {
         attr.putAll(man.getMainAttributes());
         entries.putAll(man.getEntries());
+        jv = man.jv;
     }
 
     /**
@@ -127,6 +141,23 @@
     }
 
     /**
+     * Returns the Attributes for the specified entry name, if trusted.
+     *
+     * @param name entry name
+     * @return returns the same result as {@link #getAttributes(String)}
+     * @throws SecurityException if the associated jar is signed but this entry
+     *      has been modified after signing (i.e. the section in the manifest
+     *      does not exist in SF files of all signers).
+     */
+    Attributes getTrustedAttributes(String name) {
+        Attributes result = getAttributes(name);
+        if (result != null && jv != null && ! jv.isTrustedManifestEntry(name)) {
+            throw new SecurityException("Untrusted manifest entry: " + name);
+        }
+        return result;
+    }
+
+    /**
      * Clears the main Attributes as well as the entries in this Manifest.
      */
     public void clear() {

--- a/src/share/classes/sun/misc/JavaUtilJarAccess.java	Thu Aug 09 16:15:14 2018 +0300
+++ b/src/share/classes/sun/misc/JavaUtilJarAccess.java	Wed Apr 18 22:35:30 2018 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 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
@@ -30,8 +30,10 @@
 import java.security.CodeSource;
 import java.util.Enumeration;
 import java.util.List;
+import java.util.jar.Attributes;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
+import java.util.jar.Manifest;
 
 public interface JavaUtilJarAccess {
     public boolean jarFileHasClassPathAttribute(JarFile jar) throws IOException;
@@ -41,4 +43,5 @@
     public Enumeration<JarEntry> entries2(JarFile jar);
     public void setEagerValidation(JarFile jar, boolean eager);
     public List getManifestDigests(JarFile jar);
+    public Attributes getTrustedAttributes(Manifest man, String name);
 }