CVE-2026-82416 FrankenPHP: Cross-request PHP session ID leak in worker mode when the session extension is a shared module
Attackers can hijack sessions or view other users' data in FrankenPHP worker mode if the session extension is loaded as a shared module.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-82416?
CVE-2026-82416 is a high-severity vulnerability in frankenphp, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
FrankenPHP is a modern application server for PHP. Prior to 1.12.5, FrankenPHP worker mode can retain PHP session state between requests when the session extension is loaded as a shared module and is unavailable through HAVE_PHP_SESSION at compile time. In this build configuration, frankenphp_reset_session_state() is compiled out, PS(id) can survive a request boundary, and a subsequent session_start() can ignore the new request's cookie because an identifier is already present. Under concurrent requests, session_id() can therefore return another client's identifier or a stale identifier from a previous request on the same worker thread, causing cross-user session exposure, possible session hijacking, and intermittent logout behavior. Builds with the session extension statically linked, including the official static binaries and Docker images, are not affected. This issue is fixed in version 1.12.5.
Which versions are affected by CVE-2026-82416?
3 open source packages ship an affected version, including github.com/dunglas/frankenphp.
| Package | Affected | Fixed in |
|---|---|---|
github.com/dunglas/frankenphp Go | All versions | 1.12.5 |
github.com/dunglas/frankenphp Go | All versions | 1.12.5 |
github.com/dunglas/frankenphp Go | All versions | 1.12.5 |
How do I fix CVE-2026-82416?
Upgrade github.com/dunglas/frankenphp to 1.12.5 or later.
Is CVE-2026-82416 being exploited?
There is no known exploitation of CVE-2026-82416 in the wild and no public exploit code.
Sources
Also known as GHSA-v3ph-cgqh-r8p5, GO-2026-6797.