CVE-2022-39338 : Security Advisory and Response

A stored cross-site scripting (XSS) vulnerability via Authorization Endpoint in user_oidc has been identified in Nextcloud versions prior to 1.2.1. This vulnerability could lead to a stored XSS attack vector, although its impact is limited due to the applied Content Security Policy (CSP). It has only been demonstrated to be exploitable in the Safari web browser. Nextcloud has released version 1.2.1 to address this issue, and users are strongly advised to upgrade.

Understanding CVE-2022-39338

This section delves into the specifics of CVE-2022-39338.

What is CVE-2022-39338?

The vulnerability involves improper validation of discovery URLs in user_oidc, an OpenID Connect user backend for Nextcloud, leading to a stored cross-site scripting attack.

The Impact of CVE-2022-39338

The impact is limited due to the CSP applied on the affected endpoint, with exploitation confirmed only in the Safari web browser.

Technical Details of CVE-2022-39338

Here are the technical details surrounding CVE-2022-39338.

Vulnerability Description

The vulnerability arises from the lack of proper validation of discovery URLs, opening the door to a stored XSS attack vector.

Affected Systems and Versions

Nextcloud versions prior to 1.2.1 are affected by this vulnerability.

Exploitation Mechanism

Exploitation has only been demonstrated in the Safari web browser, limiting its impact.

Mitigation and Prevention

Learn about the steps to mitigate and prevent CVE-2022-39338.

Immediate Steps to Take

Users are strongly advised to upgrade to Nextcloud version 1.2.1 to protect against this vulnerability. For users unable to upgrade, avoiding the Safari web browser is recommended.

Long-Term Security Practices

To enhance security, users should regularly update their software and follow best practices to prevent XSS attacks.

Patching and Updates

Stay informed about patches and updates released by Nextcloud to address security vulnerabilities like CVE-2022-39338.