Systems, methods, and machine-readable and executable instructions are provided for attack notification. Attack notification can include receiving security-related data from a number of computing devices that are associated with a number of entities through a communication link and analyzing a first portion of the security-related data that is associated with a first entity from the number of entities to determine whether the first entity has experienced an attack. Attack notification can include analyzing a second portion of the security-related data that is associated with a second entity from the number of entities and the first portion of the security-related data that is associated with the first entity to determine whether the second entity is experiencing the attack. Attack notification can include notifying, through the communication link, the second entity that the second entity is experiencing the attack if it is determined that the second entity is experiencing the attack.