End-of-life software is a product the vendor no longer maintains, patches, or officially supports. Once software reaches this stage, newly discovered bugs and security weaknesses usually stay open unless the organization can replace the product or build its own compensating controls.
In cyber security, end-of-life software is dangerous because attackers often target it precisely because fixes no longer arrive. A single unpatched flaw can remain exploitable for years, especially in systems that are hard to upgrade, such as laboratory, industrial, or legacy business environments. Defenders may still reduce risk with network segmentation, strict access controls, monitoring, and file integrity checks, but those measures do not remove the underlying vulnerability. In practice, the safest response is to migrate away from unsupported software before it becomes the easiest path into a trusted workflow.