CVE-2024-4990: A Deep Dive Into the Vulnerability in yiisoft/yii2 v2..48

This post presents an in-depth analysis of the vulnerability found in the yiisoft/yii2 version 2..48. This vulnerability, identified as CVE-2024-4990, exists within the base Component class of the Yii2 framework, specifically in the __set() magic method. In this post, we will discuss how this vulnerability occurs, show a code snippet demonstrating the issue, and provide links to original references for further understanding of the issue. Lastly, we will describe the potential exploit details and attack vectors this issue exposes.

Vulnerability Details

In short, the __set() magic method does not properly validate that the value passed to it is a valid Behavior class name or configuration. This validation oversight allows an attacker to instantiate arbitrary classes with custom parameters and invoke setter methods of their choosing. Depending on the installed dependencies within an application using this Yii2 framework version, an attacker can potentially execute various types of attacks, including arbitrary code execution, sensitive information disclosure, and unauthorized access.

Code Snippet

Here is a code snippet that demonstrates the problematic behavior in the Yii2 framework's base Component class:

public function __set($name, $value)
{
    $setter = 'set' . $name;
    if (method_exists($this, $setter)) {
        $this->$setter($value);
    } elseif ($this->hasEvent($name)) {
        // Issue occurs here: any class can be attached as a behavior
        $this->attachBehavior($name, $value);
    } else {
        throw new InvalidCallException('Setting unknown property: ' . get_class($this) . '::' . $name);
    }
}

As seen in the code snippet above, the __set() method is not validating that the $value passed is a valid Behavior class name or configuration before it's attached as a behavior. This is the crux of the vulnerability in this version of Yii2.

Original References

For further understanding and confirmation of the vulnerability, please refer to the following resources:

1. The official Yii2 GitHub repository: https://github.com/yiisoft/yii2
2. Researcher's report on the vulnerability: [https://example.com/researcher-report]() (Note: This is a placeholder link since we don't have a real reference for a researcher's report. In practice, a link to the person or group who discovered/reported the vulnerability would go here.)

Exploit Details

As previously mentioned, the exploitation of this vulnerability can have serious consequences, depending on the installed dependencies within the affected application. Here is a summary of the potential attack vectors:

1. Arbitrary code execution: By instantiating arbitrary classes with custom parameters, an attacker can potentially execute arbitrary code within the context of the application.
2. Sensitive information disclosure: Depending on the internals of the custom classes instantiated by the attacker, sensitive information, such as user data or environment variables, may be leaked.
3. Unauthorized access: An attacker who can instantiate arbitrary classes or manipulate existing ones within the application may be able to escalate their privileges, bypass security controls, and subsequently gain unauthorized access to various application resources and functions.

Conclusion

The vulnerability (CVE-2024-4990) present in the yiisoft/yii2 version 2..48 enables attackers to instantiate arbitrary classes with custom parameters and invoke setter methods due to insufficient validation performed by the __set() magic method. Exploiting this issue can lead to several severe attack vectors, including arbitrary code execution, sensitive data disclosure, and unauthorized access. Maintaining awareness of and patching this vulnerability in affected applications is crucial to ensure the security of both the application and its users.

Timeline

Published on: 03/20/2025 10:15:32 UTC