diff --git a/mozilla/modules/plugin/base/src/ns4xPlugin.cpp b/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
index 07510bd3c99..36cedbb16a9 100644
--- a/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
+++ b/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
@@ -975,6 +975,21 @@ _geturl(NPP npp, const char* relativeURL, const char* target)
   ("NPN_GetURL: npp=%p, target=%s, url=%s\n", (void *)npp, target,
    relativeURL));
 
+  // Block Adobe Acrobat from loading URLs that are not http:, https:,
+  // or ftp: URLs if the given target is null.
+  if (target == nsnull && relativeURL &&
+      (strncmp(relativeURL, "http:", 5) != 0) &&
+      (strncmp(relativeURL, "https:", 6) != 0) &&
+      (strncmp(relativeURL, "ftp:", 4) != 0)) {
+    ns4xPluginInstance *inst = (ns4xPluginInstance *) npp->ndata;
+
+    const char *name = nsPluginHostImpl::GetPluginName(inst);
+
+    if (name && strstr(name, "Adobe") && strstr(name, "Acrobat")) {
+      return NPERR_NO_ERROR;
+    }
+  }
+
   return MakeNew4xStreamInternal (npp, relativeURL, target,
                                   eNPPStreamTypeInternal_Get);
 }
diff --git a/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp b/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
index c05c800eaba..243149ecb07 100644
--- a/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
+++ b/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
@@ -2566,6 +2566,20 @@ nsPluginHostImpl::GetInst()
   return sInst;
 }
 
+// static
+const char *
+nsPluginHostImpl::GetPluginName(nsIPluginInstance *aPluginInstance)
+{
+  nsActivePlugin *plugin =
+    gActivePluginList ? gActivePluginList->find(aPluginInstance) : nsnull;
+
+  if (plugin && plugin->mPluginTag) {
+    return plugin->mPluginTag->mName;
+  }
+
+  return nsnull;
+}
+
 
 ////////////////////////////////////////////////////////////////////////
 NS_IMETHODIMP nsPluginHostImpl::GetValue(nsPluginManagerVariable aVariable, void *aValue)
@@ -6699,7 +6713,7 @@ nsresult nsPluginHostImpl::AddPrefObserver()
 
 ////////////////////////////////////////////////////////////////////////////////////
 nsresult nsPluginStreamListenerPeer::ServeStreamAsFile(nsIRequest *request,
-                                                        nsISupports* aContext)
+                                                       nsISupports* aContext)
 {
   if (!mInstance)
     return NS_ERROR_FAILURE;
diff --git a/mozilla/modules/plugin/base/src/nsPluginHostImpl.h b/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
index 9b032e32235..fe486a5b4fe 100644
--- a/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
+++ b/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
@@ -213,6 +213,8 @@ public:
 
   NS_DECL_ISUPPORTS
 
+  static const char *GetPluginName(nsIPluginInstance *aPluginInstance);
+
   //nsIPluginManager interface - the main interface nsIPlugin communicates to
 
   NS_IMETHOD