The set of vulnerabilities is dubbed PHP2Shell and disclosure is scheduled for 14:00 UTC with attacks expected to follow soon after.
It is adviced to take offline every non-vital services until the patch has been installed (or the Docker image has been updated with a patched version of PHP)
Update: fix is out https://www.php.net/archive/2026.php#2026-10-21-5
They originally tried to keep it secret but it got leaked. Initial reports were only that CVSS was 9.2 and it was a permissionless remote code execution exploit. After it got leaked what the exploit was, they gave up.