Index: /trunk/doc/manual/en_US/user_GuestAdditions.xml
===================================================================
--- /trunk/doc/manual/en_US/user_GuestAdditions.xml	(revision 57606)
+++ /trunk/doc/manual/en_US/user_GuestAdditions.xml	(revision 57607)
@@ -1855,5 +1855,9 @@
       <computeroutput>Guest/RAM/Usage/Shared</computeroutput> will return the
       amount of fused memory for a given VM. Please refer to <xref
-      linkend="metrics" /> for information on how to query metrics.</para>
+        linkend="metrics" /> for information on how to query metrics.</para>
+
+      <note><para>Enabling Page Fusion might improve the chances for malicious
+       guests to successfully attack other VMs running on the same host using
+       side-channel attacks, see <xref linkend="pot-insecure"/>.</para></note>
     </sect2>
   </sect1>
Index: /trunk/doc/manual/en_US/user_Security.xml
===================================================================
--- /trunk/doc/manual/en_US/user_Security.xml	(revision 57606)
+++ /trunk/doc/manual/en_US/user_Security.xml	(revision 57607)
@@ -306,5 +306,5 @@
     -->
 
-    <sect2>
+    <sect2 id="pot-insecure">
     <title>Potentially insecure operations</title>
 
@@ -326,4 +326,14 @@
           network the first question to answer is how both VMs can securely
           access the same virtual disk image(s) with a reasonable performance. </para>
+        </listitem>
+
+        <listitem>
+          <para>When Page Fusion (see <xref linkend="guestadd-pagefusion"/>)
+          is enabled, a malicious guest doing a side-channel attack could be
+          able to determine the address space layout of another guest running
+          on the same host. This would improve the chances of the malicious guest
+          to take advantage of other attack vectors he might have against the
+          target VM. To prevent potential malcious guest process from doing
+          such side-channel attacks, Page Fusion should be disabled.</para>
         </listitem>