It has been discovered that the extension "OpenID Connect Authentication" (oidc) is susceptible to Authentication Bypass.

Problem Description

The authentication service of the extension does not verify the OpenID Connect authentication state from the user lookup chain. Instead, the authentication service authenticates every valid frontend user from the user lookup chain, where the  frontend user field “tx_oidc” is not empty.

In scenarios, where either ext:felogin is active or where $GLOBALS['TYPO3_CONF_VARS'][‘FE’][‘checkFeUserPid’] is disabled, an attacker can login to OpenID Connect frontend user accounts by providing a valid username and any password. 

Solution

An updated version 2.1.0 is  available from the TYPO3 extension manager, packagist and at  

https://extensions.typo3.org/extension/download/oidc/2.1.0/zip

Users of the extension are advised to update the extension as soon as possible.

Credits

Thanks to Markus Klein for reporting and fixing the vulnerability and to Xavier Perseguers for providing an updated version of the extension.

General Advice

Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.