Istio (https://istio.io/) is a powerful open platform used to create, manage and secure microservices. It is essential in facilitating communication between services while providing essential features such as load balancing, authentication, and monitoring. A significant vulnerability has been identified in versions of the Istio 1.15.x branch prior to the 1.15.3 release. This vulnerability, labeled CVE-2022-39388, allows for user impersonation and bypassing of security controls.

Vulnerability Details

A user who has localhost access to the Istiod control plane can exploit this vulnerability to impersonate any workload identity within the Istio service mesh. This allows the attacker to bypass Istio's security mechanisms and gain unauthorized access to services or areas within the application by posing as a legitimate workload.

The root cause of the vulnerability lies in the XDS (eXtensible Data Source) protocol implementation in the Istio control plane. The XDS protocol is responsible for propagating the configuration from the control plane to the data plane (i.e., from Istiod to Envoy proxies). In versions prior to 1.15.3, the authentication and authorization for XDS clients were missing, leading to this security issue.

To give you a better understanding of the exploit, here is a code snippet illustrating how an attacker may impersonate a workload identity within the Istio service mesh:

import requests

ISTIOD_URL = "http://localhost:15012";  # Replace this with your Istiod control plane URL
TARGET_WORKLOAD = "example-service.default"  # Replace this with the target workload identity

headers = {
    "Content-Type": "application/json",
    "X-Workload-Selector": f"app={TARGET_WORKLOAD}",

response = requests.post(f"{ISTIOD_URL}/adsc", headers=headers)

if response.status_code == 200:
    print(f"Successfully impersonated {TARGET_WORKLOAD}")
    print("Failed to impersonate target workload")

Please note that the above code is for demonstration purposes only and should not be used to carry out malicious actions.

Affected Versions

All Istio versions belonging to the 1.15.x branch prior to 1.15.3 are affected by this vulnerability.


Istio has released a patch to address this critical vulnerability in the 1.15.3 version. It is strongly recommended to upgrade your Istio deployments to version 1.15.3 or later to protect against this vulnerability. You can refer to the official upgrade guide provided by Istio at https://istio.io/latest/docs/setup/upgrade/ for instructions on how to safely update your system.


There are no known workarounds for this vulnerability. Upgrading to a patched version is the only known solution.


1. Istio Official Site: https://istio.io/
2. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-39388
3. Istio GitHub Repository: https://github.com/istio/istio
4. Istio Security Bulletin: https://istio.io/latest/news/security/

In conclusion, upgrading your Istio deployment to version 1.15.3 or later is crucial in mitigating the risk posed by CVE-2022-39388. Regularly updating your systems and keeping an eye on security bulletins can help ensure that your microservices remain protected from vulnerabilities and other security threats.


Published on: 11/10/2022 20:15:00 UTC
Last modified on: 11/15/2022 20:21:00 UTC