Improper Synchronization

This vulnerability occurs when a multi-threaded or multi-process application allows shared resources to be accessed by multiple threads or processes simultaneously, without proper safeguards to enforce exclusive access.

Synchronization is the set of techniques that prevent multiple threads or processes from interfering with each other when they need to use the same resource, like a variable, file, or memory location. Since many operations on these resources cannot be performed in a single, atomic step, you need mechanisms like locks, mutexes, or semaphores to guarantee that one thread completes its entire sequence of operations before another can begin. Without this coordination, the application's behavior becomes unpredictable and unstable. Improper synchronization directly leads to race conditions, where the final state of the resource depends on the unpredictable timing of thread execution. This can corrupt data, crash the program, create security bypasses, or cause a denial of service. As a developer, you must identify all shared resources in your concurrent code and explicitly protect them with appropriate synchronization primitives to ensure only one thread can access them at a time.