Auth0 Support Center - MFA Enrollment Devices Named as "K"

MFA Enrollment Devices Named as "K"

Sep 10, 2025

Overview

Some users' device information when using MFA, such as biometrics, is named "K." Webauthn should pull this information from the device. This naming can be confusing for end users at the time of login. This article clarifies whether there is any way to avoid this.

Applies To

Device Information
MFA Enrollments

Cause

This issue can be expected due to an Android version changing the device model details and starting to send the OS family name as "K". This can be seen present on the enrollment logs for these users in the user agent string.

The Chromium browser for Android phones and tablets was updated, and the user agent no longer includes the Android version and the device model.

As an example, it changed from:

Mozilla/5.0 (Linux; Android <androidVersion>; <deviceModel>)
AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/<majorVersion>.<minorVersion> <deviceCompat>
Safari/537.36

To:

Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/<majorVersion>.0.0.0 <deviceCompat> Safari/537.36

The Auth0's SDKs parser returns "K" which is the OS family used as the name. It is most likely to see it on tenant logs "g_auth_succeed" where the K is listed in the user agent string. As an example:

{
...,
"type": "gd_auth_succeed",
"description": "Guardian - First factor authentication succeed (webauthn)",
"details": {
"request": {
"userAgent": "Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Mobile Safari/537.36",
...
}

Solution

Since this depends on Android sending the device information, there is nothing that can be configured on the Auth0 side to avoid this naming. However, our Engineering has already added a backlog item to provide a more user-friendly device name, if possible, for these cases.