YesWiki is a wiki system written in PHP. Prior to version 4.6.6, YesWiki through the latest development branch contains a SQL injection vulnerability in ReactionManager::deleteUserReaction() that allows any authenticated user to inject arbitrary SQL via the {idreaction} and {id} URL path parameters. The parameters are concatenated directly into a SQL LIKE clause without escaping or parameterization. This issue has been patched in version 4.6.6.