This diff adds a link to https://www.openbsd.org/errata66.html on https://www.openbsd.org/security.html
I noticed this when reading the 6.6 announcement email.
Index: security.html =================================================================== RCS file: /cvs/www/security.html,v retrieving revision 1.442 diff -u -p -r1.442 security.html --- security.html 1 Jun 2019 23:12:51 -0000 1.442 +++ security.html 28 Oct 2019 20:14:00 -0000 @@ -72,7 +72,8 @@ For security advisories for specific rel <a href="errata62.html">6.2</a>, <a href="errata63.html">6.3</a>, <a href="errata64.html">6.4</a>, -<a href="errata65.html">6.5</a>. +<a href="errata65.html">6.5</a>, +<a href="errata66.html">6.6</a>. <br> <hr>