nheko is a desktop client for the Matrix communication application. All versions below 0.10.2 are vulnerable homeservers inserting malicious secrets, which could lead to man-in-the-middle attacks. Users can upgrade to version 0.10.2 to protect against this issue. As a workaround, one may apply the patch manually, avoid doing verifications of one's own devices, and/or avoid pressing the request button in the settings menu.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.