diff --git a/mozilla/modules/plugin/base/src/ns4xPlugin.cpp b/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
index ea2a6bca2c4..16a7051ba31 100644
--- a/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
+++ b/mozilla/modules/plugin/base/src/ns4xPlugin.cpp
@@ -1120,6 +1120,21 @@ _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 73f78061c51..42560243950 100644
--- a/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
+++ b/mozilla/modules/plugin/base/src/nsPluginHostImpl.cpp
@@ -2571,6 +2571,20 @@ nsPluginHostImpl::nsPluginHostImpl()
   mCachedPlugins = nsnull;
 }
 
+// static
+const char *
+nsPluginHostImpl::GetPluginName(nsIPluginInstance *aPluginInstance)
+{
+  nsActivePlugin *plugin =
+    gActivePluginList ? gActivePluginList->find(aPluginInstance) : nsnull;
+
+  if (plugin && plugin->mPluginTag) {
+    return plugin->mPluginTag->mName;
+  }
+
+  return nsnull;
+}
+
 
 ////////////////////////////////////////////////////////////////////////
 nsPluginHostImpl::~nsPluginHostImpl()
diff --git a/mozilla/modules/plugin/base/src/nsPluginHostImpl.h b/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
index e101f7b685f..eb164960d2a 100644
--- a/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
+++ b/mozilla/modules/plugin/base/src/nsPluginHostImpl.h
@@ -195,6 +195,8 @@ public:
 
   NS_DECL_ISUPPORTS
 
+  static const char *GetPluginName(nsIPluginInstance *aPluginInstance);
+
   //nsIPluginManager interface - the main interface nsIPlugin communicates to
 
   NS_IMETHOD