“Critical” is the highest. A link to the list of severities is smack in the middle of the message.<p>&gt; Please see the following page for further details of severity levels: <a href="https:&#x2F;&#x2F;www.openssl.org&#x2F;policies&#x2F;secpolicy.html" rel="nofollow">https:&#x2F;&#x2F;www.openssl.org&#x2F;policies&#x2F;secpolicy.html</a>