Multi-AV scanning is the practice of checking a file with several antivirus engines instead of relying on one. Different engines use different signatures, heuristics, and behavioral rules, so a file missed by one product may still be flagged by another. This makes the technique useful for inbound email gateways, file transfer systems, sandboxes, and content inspection tools.
In cyber security, multi-AV scanning helps reduce the chance that malicious documents, archives, or scripts reach users or operational systems. It is especially valuable in high-consequence environments, where a single missed file can cause disruption. Attackers try to evade detection by changing file structure, packing malware, or using new variants that are not yet widely known. Defenders use multi-AV scanning to raise detection coverage, but it is not a guarantee: engines can disagree, and clean files can still be blocked. It works best as one layer in a broader control stack that may also include CDR, sandboxing, and manual review.