CVE-2026-59989 Phalcon Volt compiler `join` filter compile-time PHP code injection (SSTI lead to RCE)
Attackers can inject PHP code via Volt template join filters, leading to remote code execution when templates are rendered.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59989?
CVE-2026-59989 is a critical code injection vulnerability in cphalcon, published on 21 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Phalcon is a high-performance, full-stack PHP framework. In 5.15.0 and earlier, resolveFilter in phalcon/Mvc/View/Engine/Volt/Compiler.zep builds the join filter by inserting the raw separator and array token values into generated PHP without passing them through expression(). An attacker who can influence Volt template source can place quote-breaking content in a join argument, inject PHP into the compiled cache file, and execute it when Phalcon\Mvc\View\Engine\Volt::render() loads the template. This issue is fixed in version 5.16.0.
Which versions are affected by CVE-2026-59989?
2 open source packages ship an affected version, including phalcon/cphalcon.
| Package | Affected | Fixed in |
|---|---|---|
phalcon/cphalcon Packagist | All versions | 5.16.0 |
phalcon/cphalcon Packagist | All versions | 5.16.0 |
How do I fix CVE-2026-59989?
Upgrade phalcon/cphalcon to 5.16.0 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-59989 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59989 exists.
Sources
Also known as GHSA-hrwp-4hh9-c8r8.