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PHP2Shell in mailcow: is it affected and how to fix it

How to check the PHP version mailcow 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.

docker compose exec php-fpm-mailcow php -v

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 mailcow

Run ./update.sh in the mailcow directory and confirm the PHP version in the php-fpm container.
Install the vendor's fixed release or packages listed above.
Restart every PHP process (PHP-FPM pools, Apache with mod_php, LiteSpeed lsphp, queue workers); a running process keeps the old PHP in memory.
Confirm the running version again with the check commands.

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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 mailcow affected by PHP2Shell?

Affected until you install the vendor's fixed release. mailcow bundles PHP and ships 8.2.35 in its 2026-10 release.

Does updating mailcow 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 mailcow 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 mailcow 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.

← All products that bundle PHP

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.