Primary definition
An attack that exploits a previously unknown hardware, firmware, or software vulnerability.
Also known as0-day attack · zero-day exploit · zero-day vulnerability · 0-day exploit · day zero attack
3 sources cited4 related termsReviewed Aug 10, 2026
— Committee on National Security Systems Glossary CNSSI 4009-2015View source
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CNSSGC
An attack that exploits a previously unknown hardware, firmware, or software vulnerability.
Committee on National Security Systems Glossary CNSSI 4009-2015 · 2024
Cite this term
Permanent URL · stable across revisions
Election Security Glossary. (2026). Zero Day Attack. In Election Security Glossary. Retrieved August 20, 2026, from https://electionsecurityglossary.com/glossary/zero-day-attack
Sources
3 cited · last checked Aug 10, 2026
01
Committee on National Security Systems Glossary CNSSI 4009-2015
Committee on National Security Systems Glossary CNSSI 4009-2015
High consensus
02
March 2020 CSC Report
March 2020 CSC Report
Multi-source
03
The Cyber Glossary
The Cyber Glossary
Multi-source
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