PE headers are the structured metadata at the start of a Windows Portable Executable file, such as an .exe or .dll. They tell the operating system and security tools how to load the binary, where sections begin, what architecture it targets, and other details needed to parse the file safely.
They matter in cyber security because many defenses depend on correct PE parsing to identify malware, extract indicators, and decide whether a file can be trusted. Attackers may corrupt or tamper with PE headers to confuse scanners, slow analysis, or make a dropped file look malformed before it is fully inspected. Defenders respond by using multiple parsers, checking file hashes, validating structure, and comparing metadata against known-good samples. Broken headers are a warning sign, but not proof of malware; they are a clue that the file deserves deeper analysis.