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On Wednesday, October 21, 2026 at 14:00 UTC, the PHP project released PHP 8.5.12, 8.4.27, 8.3.36, and 8.2.35 to fix two critical vulnerabilities, both rated CVSS v4.0 9.2, that can allow unauthenticated remote code execution. The PHP security team advises: "There are no complete mitigations; updating is the only safe choice." These are bugs in the PHP runtime, not in a Composer package.

PHP2Shell is a pair of critical remote code execution (RCE) vulnerabilities in PHP, CVE-2026-109618 and CVE-2026-109619. Both score 9.2 on CVSS v4.0, and either one can let an unauthenticated attacker run code on a server that handles PHP requests. Cloudflare reports that exploitation has started. PHP shipped fixes on October 21 in 8.5.12, 8.4.27, 8.3.36 and 8.2.35. PHP 8.1 and older are out of support and won’t get an upstream release.

AI is changing how vulnerabilities are discovered and exploited for defenders and attackers alike, and the practical effect is that the time organizations have between a flaw being found and a flaw being exploited keeps shrinking. Today, we have more known vulnerabilities than at any point in history, and they’re being exploited faster than ever.

On October 21, 2026, PHP shipped emergency fixes for two flaws that let anyone on the internet run code on a PHP web server, with no login. The weakness behind them had been flagged in 2024 and then sat, partly because nobody had proved it was exploitable. In 2026, researchers working with AI models proved it within days. Exploit attempts started before the fix shipped, and details leaked a day ahead of schedule. That sequence is the real story of PHP2Shell. The bug matters, but speed matters more.

If you run Node.js, update to 26.12.1, 24.22.1 or 22.23.4 now. If you run Python, upgrade the Brotli package to 1.2.1 and brotlicffi to 1.2.1.0. If you run Bun, move to 1.4.4. All three carry a fix for CVE-2026-111497, an out-of-bounds write in Google's Brotli decoder that can let a remote, unauthenticated attacker crash a process, read its memory or potentially run code by sending it crafted compressed data. Google's CVE record scores it 9.2 under CVSS v4.0.

PHP2Shell is a pair of critical flaws in the PHP interpreter itself, each with a CVSS v4.0 score of 9.2. Both let an unauthenticated attacker run code on a web server with a single crafted web request, or a pair of them, before any application code runs. Because the bug lives in PHP, not in WordPress, Drupal or Magento, every reachable PHP endpoint on an affected server is exposed, including login pages, static forms, and health checks. Every PHP release from the last decade is affected (back to 5.4).

Two days after PHP shipped emergency patches for PHP2Shell (CVE-2026-109618 and CVE-2026-109619), the project is back with another RCE advisory: CVE-2026-115560. Looks like PHPoclypse is going to stick around till the weekend. In this blog, we break down what CVE-2026-115560 actually is, the narrow configuration that makes it exploitable, and the one-line mitigation you can apply before the weekend.