Time-of-check to time-of-use

In software development, time-of-check to time-of-use (TOCTOU, TOCTTOU or TOC/TOU) is a class of software bugs caused by a race condition involving the checking of the state of a part of a system (such as a security credential) and the use of the results of that check. TOCTOU race conditions are common in Unix between operations on the file system, but can occur in other contexts, including local sockets and improper use of database transactions.

Source: Wikipedia — Time-of-check to time-of-use (CC BY-SA 4.0)