The MonsterInsights WordPress plugin before 11.1.0 does not correctly validate the signature on one of its unauthenticated AJAX actions: when the MonsterInsights WordPress plugin before 11.1.0 is not connected to Google Analytics the HMAC signing key is empty, which lets unauthenticated attackers forge a valid signature and overwrite a MonsterInsights WordPress plugin before 11.1.0 configuration value, disrupting the MonsterInsights WordPress plugin before 11.1.0s server-side analytics in Manual GA4 mode.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.