CVE-2023-50714: Yiiframework YII2-Authclient

High severity, CVSS 8.8. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Yiiframework YII2-Authclient: before 2.2.15 (fixed in 2.2.15)

Published 2023-12-22. Last modified 2026-06-17.