zero-day
adjective
ze·ro-day
ˈzir-(ˌ)ō-ˈdā 
ˈzē-(ˌ)rō-
computing
: of, relating to, or being a vulnerability (as in a computer or computer system) that is discovered and exploited (as by cybercriminals) before it is known to or addressed by the maker or vendor
Thus, in the parlance of the trade, these vulnerabilities are known as "zero-day exploits," because it has been zero days since they have been uncovered and fixed.—
James Bamford
James BamfordThere's a zero-day vulnerability in RealPlayer and Internet Explorer that allows malicious code to be installed …—Mark Hopkins
Mark Hopkins… most of what's on the black market doesn't have that zero-day freshness. Criminals typically target older vulnerabilities, for which fixes have already been released …—Lev Grossman
Lev GrossmanExamples of zero-day in a Sentence
Recent Examples on the Web
Some cyber attacks begin with a dangerous email landing in your inbox, others might take a more direct, brute force approach, or exploit multiple zero-day vulnerabilities in Windows.
—Davey Winder, Forbes, 16 Mar. 2025
Traders taking advantage of highly speculative zero-day options represent another challenge for Nvidia shares.
—Kevin Stankiewicz, CNBC, 14 Mar. 2025
The scariest ransomware is the zero-day type that’s never been detected before.
—PCMAG, 4 Mar. 2025
Instead of just one operating system being compromised, the series imagines a sophisticated attack exploiting multiple zero-day vulnerabilities simultaneously.
—Gordon G. Chang, Newsweek, 4 Mar. 2025
See All Example Sentences for zero-day
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Davey Winder, Forbes, 16 Mar. 2025
Traders taking advantage of highly speculative zero-day options represent another challenge for Nvidia shares.
—Kevin Stankiewicz, CNBC, 14 Mar. 2025
The scariest ransomware is the zero-day type that’s never been detected before.
—PCMAG, 4 Mar. 2025
Instead of just one operating system being compromised, the series imagines a sophisticated attack exploiting multiple zero-day vulnerabilities simultaneously.
—Gordon G. Chang, Newsweek, 4 Mar. 2025
See All Example Sentences for zero-day
Articles Related to zero-day
Cite this Entry
“Zero-day.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/zero-day. Accessed 24 Mar. 2025.
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