diff --git a/chapter06/ed-exp.xml b/chapter06/ed-exp.xml
index 0914671f5..41e4d35e4 100644
--- a/chapter06/ed-exp.xml
+++ b/chapter06/ed-exp.xml
@@ -1,8 +1,10 @@
 <sect2>
 <title>Command explanations</title>
 
-<para>The sed commands fix a symlink vulnerability in ed. See
-<ulink url="http://www.securityfocus.com/templates/advisory.html?id=3308">
-http://www.securityfocus.com/templates/advisory.html?id=3308</ulink> for
-more information.</sect2>
+<para>The sed commands fix a symlink vulnerability in ed. The ed
+executable creates files in /tmp with predictable names. By using
+various symlink attacks, it is possible to have ed write to files 
+it should not, change the permissions of various files, etc.</para>
+
+</sect2>