2026-018: Critical Vulnerabilities in PHP

On 20 October 2026, the PHP project announced an upcoming security release addressing two critical vulnerabilities in PHP. Public reports indicated that these vulnerabilities could lead to remote code execution. The PHP team released the fixes today, 21 October 2026 at 13:30 UTC, in PHP versions 8.5.12, 8.4.27, 8.3.36 and 8.2.35. Both vulnerabilities can allow unauthenticated remote code execution. Technical details are now being discussed publicly, and initial proofs of concept (PoCs) have begun to circulate. This raises the likelihood that attackers are already exploiting the vulnerabilities. CERT-EU advises organisations to patch affected assets immediately. Where that is not feasible, organisations should consider isolating internet-facing applications from public networks until a fix is applied and verified.