CVE-2023-50714

yii2-authclient is an extension that adds OpenID, OAuth, OAuth2 and OpenId Connect consumers for the Yii framework 2.0. In yii2-authclient prior to version 2.2.15, the Oauth2 PKCE implementation is vulnerable in 2 ways. First, the authCodeVerifier should be removed after usage (similar to authState). Second, there is a risk for a downgrade attack if PKCE is being relied on for CSRF protection. Version 2.2.15 contains a patch for the issue. No known workarounds are available.