There's a new security issue in the wild, identified as CVE-2022-3172, that has been discovered in kube-apiserver. This issue allows an aggregated API server to redirect client traffic to any URL, potentially leading to the client executing unexpected actions or forwarding their API server credentials to third parties. In this post, we will dissect the vulnerability, explore its impact, and discuss ways to protect your systems from potential exploits.


Kube-apiserver is a critical component of Kubernetes and responsible for handling all communication between different nodes in a cluster. When a client connects to kube-apiserver, it establishes communication through the aggregated API server that the kube-apiserver proxies.

The Vulnerability

The vulnerability exposed in CVE-2022-3172 resides in the aggregated API server, which currently permits a malicious API server to proxy the client's traffic to unauthorized destinations. This can lead to various consequences, such as:

A sample code snippet illustrating this vulnerability is shown below

// API server code
func redirectToMaliciousSite(res http.ResponseWriter, req *http.Request) {
	// Redirect the client's request to a malicious site
	http.Redirect(res, req, "";, http.StatusFound)

Original References

For more information about this vulnerability and its history, you can refer to the following sources:

1. Official CVE-2022-3172 description
2. The Kubernetes Security Announcement
3. Kubernetes GitHub Repository

Exploit Details

To exploit this vulnerability, an attacker needs access to an aggregated API server and the ability to modify the server's configuration. They can then configure the server to redirect client connections to unauthorized destinations, potentially causing unexpected behavior for the affected client, or possibly exfiltrating sensitive data.

For example, consider an attacker who has configured an aggregated API server to redirect client's traffic to a malicious site capable of capturing their kube-apiserver credentials. The attacker could then use these stolen credentials to perform various malicious activities, such as launching attacks on the system or gaining unauthorized access to other resources.

Mitigation and Protection

The good news is that there are ways to protect your systems from the effects of CVE-2022-3172. Here are a few steps you can take:

1. Update your Kubernetes cluster immediately: The Kubernetes team has released patches for this vulnerability, so make sure to update your cluster to the latest patch version available. Follow the official patch documentation to ensure a smooth upgrade process.
2. Limit access to aggregated API servers: Ensure that only authorized users with proper access permissions can interact with aggregated API servers, reducing the chances of an attacker gaining access.
3. Monitor your systems: Continuously monitor your Kubernetes cluster, paying close attention to any suspicious requests or redirects involving the aggregated API server. Implementing intrusion detection systems (IDS) and intrusion prevention systems (IPS) can help your security team to identify and react to any possible threats.


CVE-2022-3172 highlights the potential harm of an aggregated API server vulnerability in kube-apiserver, which can lead to unexpected actions, loss of authentication credentials, and unauthorized third-party access to sensitive data. Protection against this vulnerability involves updating your Kubernetes cluster, restricting access to aggregated API servers, and closely monitoring your systems. Stay proactive to maintain the security of your cluster and prevent attackers from exploiting this dangerous vulnerability.


Published on: 11/03/2023 20:15:08 UTC
Last modified on: 11/14/2023 16:26:22 UTC