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Glossary Security

Zero-day

A zero-day is a vulnerability unknown to the software's maker, or without an available fix, that attackers can exploit before anyone can defend against it.

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In more detail

The name refers to the vendor having had "zero days" to fix it. Once a patch is released, the flaw becomes a known vulnerability, but systems stay at risk until they are updated. Defence in depth, prompt patching, monitoring and limiting what each program can do reduce the harm of unknown flaws.

See also

  • Glossary Vulnerability
    A vulnerability is a weakness in software, hardware or a process that an attacker could exploit to do something unintended.
  • Glossary CVE
    A CVE (Common Vulnerabilities and Exposures) is a unique identifier, such as CVE-2021-44228.
  • Glossary Malware
    Malware is any software designed to harm a device or steal from its user, including viruses, worms, ransomware, spyware and trojans.
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