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PHP2Shell in IIS on Windows: is it affected and how to fix it

How to check the PHP version IIS on Windows uses

Run the command for your setup. A version at or above 8.2.35, 8.3.36, 8.4.27 or 8.5.12 in its branch is fixed; older branches are fixed only by a vendor build that says so.

C:\PHP\php.exe -v
%windir%\system32\inetsrv\appcmd list config /section:system.webServer/fastCgi

The command-line php can differ from the PHP that serves the site. To be sure, check the web SAPI (a temporary phpinfo() page behind authentication, or the panel's PHP settings) and remove it afterwards. Our version checker compares a version number for you.

🔎 Got a version number? Paste it into the PHP2Shell checker →

How to fix PHP2Shell in IIS on Windows

Download the Non Thread Safe x64 zip for your branch from windows.php.net (IIS FastCGI uses NTS) and the matching Visual C++ runtime.
Stop the site or app pool, replace the PHP folder contents (keep your php.ini and extensions), then run iisreset and confirm with php -v.
If no vendor build exists, replacing the bundled PHP with an official fixed build of the same branch is the DIY route. Keep a backup of the old folder and your php.ini.
Restart the web server and re-check the version the web SAPI reports.

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If you cannot patch yet

Set session.upload_progress.enabled = 0 where applications cannot override it (php.ini, php_admin_value in the FPM pool or Apache config), and restart PHP.
On PHP 8.5, set fatal_error_backtraces = 0.
PHP's interim advice also covers memory_limit and a low post_max_size; follow the remediation page exactly, because these settings only reduce some paths.
Restrict access (VPN, IP allowlist) or take the service offline if it runs PHP 8.1 or older with no vendor backport. WAF rules help but are not a fix.

FAQ

Is IIS on Windows affected by PHP2Shell?

Affected until you install the vendor's fixed release. windows.php.net has fixed builds of all four branches. IIS does not update PHP for you: every PHP folder that IIS FastCGI points to must be replaced. PHP installed years ago with PHP Manager or Web Platform Installer stays on the version it installed.

Does updating IIS on Windows itself fix CVE-2026-109618 and CVE-2026-109619?

Only if the update contains fixed PHP. PHP2Shell is a flaw in the PHP interpreter, so what matters is the PHP that IIS on Windows runs on. Check the version after updating.

Which PHP versions fix PHP2Shell?

PHP 8.2.35, 8.3.36, 8.4.27 and 8.5.12, released 21 October 2026. PHP 8.1 and older get no release from the PHP project; only vendor builds with a backport (or a self-built source patch for 7.4, 8.0 and 8.1) fix them.

What if IIS on Windows has no fix yet?

Keep its PHP-based web interface off the internet (VPN or IP allowlist), apply PHP's interim settings such as disabling session upload progress, and install the vendor update as soon as it ships. Interim settings reduce risk but are not a fix.

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Sources

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Unofficial summary of public sources. This site is not affiliated with the vendor or the PHP project and hosts no exploit code.