diff --git a/doc/src/sgml/release-9.3.sgml b/doc/src/sgml/release-9.3.sgml
index 1b923aa6d6e..cd4eaf6e27e 100644
--- a/doc/src/sgml/release-9.3.sgml
+++ b/doc/src/sgml/release-9.3.sgml
@@ -23,7 +23,23 @@
    </para>
 
    <para>
-    However, if you are upgrading from a version earlier than 9.3.18,
+    However, if you run an installation in which not all users are mutually
+    trusting, or if you maintain an application or extension that is
+    intended for use in arbitrary situations, it is strongly recommended
+    that you read the documentation changes described in the first changelog
+    entry below, and take suitable steps to ensure that your installation or
+    code is secure.
+   </para>
+
+   <para>
+    Also, the changes described in the second changelog entry below may
+    cause functions used in index expressions or materialized views to fail
+    during auto-analyze, or when reloading from a dump.  After upgrading,
+    monitor the server logs for such problems, and fix affected functions.
+   </para>
+
+   <para>
+    Also, if you are upgrading from a version earlier than 9.3.18,
     see <xref linkend="release-9-3-18">.
    </para>
   </sect2>
@@ -33,6 +49,64 @@
 
    <itemizedlist>
 
+    <listitem>
+     <para>
+      Document how to configure installations and applications to guard
+      against search-path-dependent trojan-horse attacks from other users
+      (Noah Misch)
+     </para>
+
+     <para>
+      Using a <varname>search_path</varname> setting that includes any
+      schemas writable by a hostile user enables that user to capture
+      control of queries and then run arbitrary SQL code with the
+      permissions of the attacked user.  While it is possible to write
+      queries that are proof against such hijacking, it is notationally
+      tedious, and it's very easy to overlook holes.  Therefore, we now
+      recommend configurations in which no untrusted schemas appear in
+      one's search path.  Relevant documentation appears in
+      <xref linkend="ddl-schemas-patterns"> (for database administrators and users),
+      <xref linkend="libpq-connect"> (for application authors),
+      <xref linkend="extend-extensions-style">  (for extension authors), and
+      <xref linkend="sql-createfunction"> (for authors
+      of <literal>SECURITY DEFINER</literal> functions).
+      (CVE-2018-1058)
+     </para>
+    </listitem>
+
+    <listitem>
+     <para>
+      Avoid use of insecure <varname>search_path</varname> settings
+      in <application>pg_dump</application> and other client programs
+      (Noah Misch, Tom Lane)
+     </para>
+
+     <para>
+      <application>pg_dump</application>,
+      <application>pg_upgrade</application>,
+      <application>vacuumdb</application> and
+      other <productname>PostgreSQL</productname>-provided applications were
+      themselves vulnerable to the type of hijacking described in the previous
+      changelog entry; since these applications are commonly run by
+      superusers, they present particularly attractive targets.  To make them
+      secure whether or not the installation as a whole has been secured,
+      modify them to include only the <structname>pg_catalog</structname>
+      schema in their <varname>search_path</varname> settings.
+      Autovacuum worker processes now do the same, as well.
+     </para>
+
+     <para>
+      In cases where user-provided functions are indirectly executed by
+      these programs &mdash; for example, user-provided functions in index
+      expressions &mdash; the tighter <varname>search_path</varname> may
+      result in errors, which will need to be corrected by adjusting those
+      user-provided functions to not assume anything about what search path
+      they are invoked under.  That has always been good practice, but now
+      it will be necessary for correct behavior.
+      (CVE-2018-1058)
+     </para>
+    </listitem>
+
     <listitem>
      <para>
       Fix misbehavior of concurrent-update rechecks with CTE references