PHP 8.5.12, 8.4.27, 8.3.36 and 8.2.35 are the php security update for two critical remote code execution flaws, released on 21 October 2026. Read your full PHP version now, and update if it is lower than the fixed release for your branch. A green WordPress Site Health check does not prove you are patched, and PHP 8.1 and older get no fix from PHP.

The PHP critical security release is due on 21 October 2026 at 14:00 UTC and fixes two flaws rated CVSS 9.2. PHP has not named the affected versions yet, so treat every WordPress site as exposed until it does. Check your full PHP version now, back up, and update as soon as the fixed version for your branch is published. A green Site Health PHP check does not prove you are patched.

The headers already sent warning means PHP had already sent a byte of page output when WordPress tried to send a header or a cookie. Read the path after "output started at" first, because it names the file and line where that byte left. A line number of 1 points to a BOM, a line near the end points to text after a closing tag, and a core file points to a notice printed above it. In our lab a 3 byte BOM produced six warnings and no login.

WordPress prints "Sorry, you are not allowed to access this page." from one line in core, after one function answers no. That function refuses for three reasons: the page is not registered, your account has no role, or your role is too low. Open the Dashboard first. If it loads, check the plugin behind the address. If it fails too, the role records carry the wrong prefix.
