CVE-2026-66569 in Kicker
Summary
by MITRE • 10/10/2026
Unauthenticated PHP Object Injection in Kicker <= 2.2.1 versions.
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Analysis
by VulDB Data Team • 10/10/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within the Kicker application, specifically affecting versions up to and including 2.2.1, represents a critical security deficiency rooted in improper handling of serialized data inputs. This type of vulnerability arises when an application accepts user-supplied input that is directly passed into a deserialization function without adequate validation or sanitization mechanisms. In the context of PHP applications, this often involves functions such as unserialize() where attacker-controlled strings can be crafted to instantiate arbitrary objects with malicious properties. The absence of authentication requirements for exploiting this flaw significantly elevates its severity, allowing any remote actor on the network to trigger the vulnerability without needing valid credentials or prior interaction with a legitimate user session.
From a technical perspective, PHP object injection exploits the internal mechanisms of the language where class definitions map specific property names and values to executable methods known as magic methods. When an attacker provides a carefully constructed serialized string containing references to existing classes within the application's codebase or included libraries, they can manipulate these objects during the deserialization process. This manipulation often leads to unintended side effects such as arbitrary file reads, remote command execution, or denial of service conditions depending on which class properties are overwritten and what methods are invoked automatically by the PHP engine. The core technical flaw lies in the lack of integrity checks on the serialized payload, allowing attackers to forge objects that bypass expected application logic flows.
The operational impact of this vulnerability is severe due to its unauthenticated nature. An attacker can potentially achieve full remote code execution on the underlying server hosting the Kicker application if they can identify suitable gadget chains within the available PHP classes and dependencies. This could result in complete compromise of the web server, leading to data exfiltration, installation of persistent backdoors, or use of the compromised system as a pivot point for further attacks against internal network resources. Additionally, even without achieving code execution, attackers might leverage this flaw to perform unauthorized actions within the application context if specific classes allow manipulation of session states or administrative functions through property overwriting.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-502 which describes Deserialization of Untrusted Data. It also maps closely to MITRE ATT&CK technique T1059 Command and Scripting Interpreter, particularly when the injection leads to execution of system commands via PHP functions like exec() or shell_exec(). Furthermore, it relates to CWE-470 Use of Externally-Controlled Input to Select Classes or Code which highlights the danger of allowing external inputs to dictate program flow through object instantiation. Understanding these mappings helps in categorizing the risk profile and prioritizing remediation efforts based on established industry standards for vulnerability management.
Mitigation strategies must focus on eliminating the root cause by avoiding deserialization of untrusted data entirely where possible. If serialization is necessary, developers should implement strict allowlists to validate class names before instantiation or use secure alternatives like JSON encoding which does not support object injection vulnerabilities. For existing deployments running Kicker versions 2.2.1 and below, immediate upgrading to the latest patched version released by the vendor is essential as it likely includes fixes for input validation logic. In cases where updating is temporarily unfeasible, implementing a Web Application Firewall with rules capable of detecting malformed serialized payloads or blocking suspicious PHP function calls can provide an additional layer of defense against exploitation attempts until permanent remediation is applied.