Memory overflow is a software flaw that happens when a program stores more data in a memory region than it was allocated. The extra data can overwrite nearby memory, leading to crashes, corrupted state, or unstable behavior. In some cases, it can also open the door to code execution if an attacker can carefully control what gets written.
This matters in cyber security because memory-overflow bugs often affect exposed services, network appliances, and authentication components where reliability is critical. Attackers may use malformed network traffic or crafted requests to trigger the flaw, causing denial of service or creating conditions for deeper compromise. Defenders respond by patching affected builds, validating inputs, limiting exposure, and monitoring for repeated crashes or unusual appliance behavior.