An issue was discovered in the Winbox service of MikroTik RouterOS long-term release v6.43.13 through v6.49.13 and stable v6.43 through v7.17.2. A patch is available in the stable release v6.49.18. A discrepancy in response size between connection attempts made with a valid username and those with an invalid username allows attackers to enumerate for valid accounts.
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.