In the OAuth2 Client extension before 0.4 for MediaWiki, a CSRF vulnerability exists due to the OAuth2 state parameter not being checked in the callback function.
https://seclists.org/bugtraq/2019/Aug/32
https://github.com/Schine/MW-OAuth2Client/releases/tag/v0.4
https://github.com/Schine/MW-OAuth2Client/commit/6a4fe4500ddd72ad4e826d9d63b2d69512bd10d1
http://www.openwall.com/lists/oss-security/2019/08/19/1