In certain embodiments, image-feature malicious-activity detection and access prevention may be facilitated, where an activity notification associated with a transaction triggers feature detection for at least one image related to a different transaction. In some embodiments, a first image (received in connection with a first transaction) may be associated with the first transaction, and a second image (received in connection with a second transaction) may be associated with a second transaction. In response to a malicious activity notification associated with the first transaction, an identifying characteristic (e.g., a facial feature) detected in the first image may be used to determine whether to prevent access to an account related to the second transaction. As an example, in response to determining that the identifying characteristic is present in the second image, access to the account related to the second transaction may be prevented.