PHP CVE-2026-109618/109619 session decode failure after arm

Detects PHP error log entries indicating a session object decode failure, which may indicate exploitation attempts of CVE-2026-109618 and CVE-2026-109619. Note - the logsource product php / service error is not defined by SigmaHQ. Map it with a processing pipeline to wherever PHP error lines land in your stack (PHP error_log file, nginx or Apache error log, PHP-FPM log, or syslog/journal).