vantage6 is an open source framework built to enable, manage and deploy privacy enhancing technologies like Federated Learning and Multi-Party Computation. Much like GHSA-45gq-q4xh-cp53, it is possible to find which usernames exist in vantage6 by calling the API routes `/recover/lost` and `/2fa/lost`. These routes send emails to users if they have lost their password or MFA token. This issue has been addressed in commit `aecfd6d0e` and is expected to ship in subsequent releases. Users are advised to upgrade as soon as a new release is available. There are no known workarounds for this vulnerability.
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.