diff --git a/plugins/providers/virtualbox/driver/version_4_3.rb b/plugins/providers/virtualbox/driver/version_4_3.rb
index 7636d996f..b9b3badb4 100644
--- a/plugins/providers/virtualbox/driver/version_4_3.rb
+++ b/plugins/providers/virtualbox/driver/version_4_3.rb
@@ -609,9 +609,10 @@ module VagrantPlugins
         end
 
         def share_folders(folders)
+          guestOS = read_guest_property("/VirtualBox/GuestInfo/OS/Product")
           folders.each do |folder|
             hostpath = folder[:hostpath]
-            if Vagrant::Util::Platform.windows?
+            if Vagrant::Util::Platform.windows? && guestOS != "SunOS"
               hostpath = Vagrant::Util::Platform.windows_unc_path(hostpath)
             end
             args = ["--name",
diff --git a/plugins/providers/virtualbox/driver/version_5_0.rb b/plugins/providers/virtualbox/driver/version_5_0.rb
index 6544e8785..3c01adce7 100644
--- a/plugins/providers/virtualbox/driver/version_5_0.rb
+++ b/plugins/providers/virtualbox/driver/version_5_0.rb
@@ -613,8 +613,15 @@ module VagrantPlugins
         end
 
         def share_folders(folders)
+          guestOS = read_guest_property("/VirtualBox/GuestInfo/OS/Product")
           folders.each do |folder|
-            hostpath = Vagrant::Util::Platform.windows_path(folder[:hostpath])
+            # NOTE: Guest additions on Solaris guests do not properly handle
+            # UNC style paths so prevent conversion (See GH-7264)
+            if guestOS == "SunOS"
+              hostpath = folder[:hostpath]
+            else
+              hostpath = Vagrant::Util::Platform.windows_path(folder[:hostpath])
+            end
             args = ["--name",
               folder[:name],
               "--hostpath",