Vulnerability · Published Aug 21, 2026 · Assigned by GitHub_M

CVE-2026-59989Phalcon Volt compiler `join` filter compile-time PHP code injection (SSTI lead to RCE)

Critical 9.2

In plain English

A critical-severity code injection in cphalcon from phalcon. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)9.2Critical

Exploit odds (30 days)0.5%top 54.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	phalcon/cphalcon	5.16.0	GHSA-hrwp-4hh9-c8r8

Affected products (as reported)

Vendor	Product	Versions
phalcon	cphalcon	< 5.16.0

Weakness: CWE-94, CWE-1336 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References

https://github.com/phalcon/cphalcon/security/advisories/GHSA-hrwp-4hh9-c8r8 x_refsource_CONFIRM
https://github.com/phalcon/cphalcon/pull/17217 x_refsource_MISC
https://github.com/phalcon/cphalcon/commit/e434061be3b7161930476c1368c868badc71e1bd x_refsource_MISC
https://github.com/phalcon/cphalcon/releases/tag/v5.16.0 x_refsource_MISC