Using the ol' flip-flop/Range Operators worked for me: 
while (<>) {
    if ( / ^ OVERVIEW \s $/x .. / ^ AFFECTED\ PRODUCTS \s $/x ) {
        print $_ unless /( ^ OVERVIEW \s $)|( ^ AFFECTED\ PRODUCTS \s 
+$)/x;
    }
}

[download]

I added spaces to the regex because each line ends with a space. Here is the output:

This Updated Advisory is a follow-up to the original Advisory titled “
+ICSA-11-273-03—Rockwell 
RSLogix denial-of-Service Vulnerability” that was published September 
+30, 2011 on the ICS-CERT web 
page. 
ICS-CERT is aware of a public report of a denial-of-service vulnerabil
+ity in Rockwell Automation’s 
RSLogix application.  
--------- Begin Update X Part 1 of 2 -------- 
Rockwell has produced a patch that mitigates this vulnerability for al
+l affected versions of FactoryTalk 
Services Platform and RSLogix 5000. 
--------- End Update X Part 1 of 2 ----------

[download]

EDIT -- a cleaner version:

while (<>) {
    if ( / ( ^ OVERVIEW           \s $ ) /x
      .. / ( ^ AFFECTED\ PRODUCTS \s $ ) /x ) {
        chomp;
        say $_ unless $_ eq $1;
    }
}

[download]

In reply to Re: Regex problem by frozenwithjoy
in thread Regex problem by jayto

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