CVE-2021-21396: Bulk list client endpoint exposes too much metadata about a client
wire-server is an open-source back end for Wire, a secure collaboration platform. In wire-server from version 2021-02-16 and before version 2021-03-02, the client metadata of all users was exposed in the GET /users/list-clients endpoint. The endpoint could be used by any logged in user who could request client details of any other user (no connection required) as far as they can find their User ID. The exposed metadata included id, class, type, location, time, and cookie. A user on a Wire backend could use this endpoint to find registration time and location for each device for a given list of users. As a workaround, remove /list-clients from nginx config. This has been fixed in version 2021-03-02.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2021-21396?
CVE-2021-21396 is a vulnerability in wire-server, an open-source back end for Wire, a secure collaboration platform, where the client metadata of all users was exposed in the `GET /users/list-clients` endpoint.
What is the severity of CVE-2021-21396?
The severity of CVE-2021-21396 is medium, with a CVSS severity score of 6.5.
How can the CVE-2021-21396 vulnerability be exploited?
The CVE-2021-21396 vulnerability can be exploited by any logged in user who can make a request to the `GET /users/list-clients` endpoint.
How to fix CVE-2021-21396?
To fix CVE-2021-21396, it is recommended to upgrade wire-server to version 2021-03-02 or later, as this vulnerability has been addressed in that release.
Where can I find more information about CVE-2021-21396?
You can find more information about CVE-2021-21396 in the following references: [link1], [link2], [link3].