TI-2026-42773 Aliases CVE-2026-59989 GHSA-hrwp-4hh9-c8r8

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

HIGH 81CWE-1336Published 2026-08-21 · Updated 2026-08-27

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: Present
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-1336.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00543 45th percentileScored 2026-11-07

Fix Fixed cphalcon (phalcon): 5.16.0phalcon/cphalcon (Packagist): 5.16.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
phalcon	cphalcon	before 5.16.0	5.16.0	Patch available	CNA
—	phalcon/cphalcon (Packagist)	before 5.16.0	5.16.0	Patch available	GHSA-hrwp-4hh9-c8r8

cphalcon Vendorphalcon Affected before 5.16.0 Fixed in 5.16.0 Patch available CNA
phalcon/cphalcon (Packagist) Vendor— Affected before 5.16.0 Fixed in 5.16.0 Patch available GHSA-hrwp-4hh9-c8r8

Remediation

Fix · CNA cphalcon (phalcon) Fixed in 5.16.0
Fix · GHSA-hrwp-4hh9-c8r8 phalcon/cphalcon (Packagist) Fixed in 5.16.0 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-59989
2026-10-03 Alias added: GHSA-hrwp-4hh9-c8r8

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-59989

Other 5

TI-2026-41434 Phalcon: Catastrophic backtracking (ReDoS) in the default Phalcon Router route lead to remote unauthenticated DoS CVSS 4.0HIGH 8.7
TI-2026-39548 Phalcon: Non-constant-time HMAC verification in `Encryption\Crypt::decrypt` (timing side-channel) CVSS 4.0HIGH 8.2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences