zero-day

See also: zero day

English

Alternative forms

• zero day, 0-day

Pronunciation

• Audio (Australian):

  (file)

Adjective

zero-day (not comparable)

1. (computing) Of warez, released less than a day after the official product release.
   • 2020, Oliver Markus Malloy, Bad Choices Make Good Stories:

     Back then, having "zero day warez" (brand new cracked games that are not even one day old yet) on your BBS first was a big status symbol.

2. (computer security) Of a vulnerability, newly discovered, and therefore still not fixed and possibly exploited by hackers or other criminals.
   • 2010 January 18, Jack Schofield, “The IE zero-day vulnerability, Google, and you”, in The Guardian‎^[1], →ISSN:

     Although it's had tons of publicity, the IE zero-day vulnerability is so far only a real threat to people running IE6 on Windows XP, and you have to wonder about the competence of the companies actually affected by it[.]

   • 2012 August 30, Charles Arthur, “Java exploit: Asian hackers behind first attacks, says Symantec”, in The Guardian‎^[2], →ISSN:

     Zero-day flaws are a burgeoning commercial field in the underground hacker economy where some gangs work to order for commercial or government clients which want to break into systems.

   • 2026 April 18, John Thornhill, “Lunch with the FT: Dario Amodei”, in FT Weekend (Life & Arts section), London: The Financial Times Ltd., →ISSN, →OCLC, page 3:

     The company says Mythos has revealed thousands of so-called zero-day—previously undiscovered—cyber vulnerabilities in every operating system and web browser, some of them up to 27 years old.

3. (computer security) Of an exploit or its threat or an attack, benefiting from a newly found and yet unpatched or unmitigated flaw in software or hardware; using a zero-day vulnerability.
   • 2003, John Viega, Matt Messier, Secure Programming Cookbook for C and C++:

     If your software is popular and has a high demand, you will want to defend against the "zero-day" cracker.

   • 2005, Valdes et al, Recent Advances in Intrusion Detection

     Automatically creating reliable signatures of zero-day exploits is the focus of intense research efforts.

   • 2014, Michael Gregg, CASP CompTIA Advanced Security Practitioner Study Guide: Exam CAS-002‎^[3]:

     Before discussing ways to counter zero-day attacks, let's begin with the definition of what a zero-day attack is. A zero-day attack is one that the vendor does not yet know about or hasn't been fixed.

   • 2015 October 14, Alex Hern, “Flash hit by another zero-day vulnerability”, in The Guardian‎^[4], →ISSN:

     Yet again, Adobe’s Flash plugin has been hit by a “zero-day” exploit, meaning that even users with a fully up-to-date installation of the software are vulnerable to attacks.

4. Used other than figuratively or idiomatically: see zero,‎ day.

   Average residues of 1.44 and 2.18 mg/kg chlortetracycline were seen in liver and kidney, respectively, at zero-day withdrawal.

Noun

zero-day (plural zero-days)

1. (computer security) A vulnerability that has been discovered recently, and is yet unpatched or unmitigated; a zero-day vulnerability.

   New Internet Explorer zero-day exploited in Hong Kong attacks

   • 2016 August 6, Alex Hern, “NSA denies ‘Raiders of the Lost Ark' stockpile of security vulnerabilities”, in The Guardian‎^[5], →ISSN:

     America’s National Security Agency (NSA) spends upwards of $25m in a year buying previously undisclosed security vulnerabilities – known as zero days, because that’s the length of time the target has had to fix them – but the large investment may not result in as much of a collection of hacking capabilities as is widely assumed.

   • 2025 December 20, Andy Greenberg, “Hackers Stole Millions of PornHub Users’ Data for Extortion”, in Wired‎^[6], San Francisco, Calif.: Condé Nast Publications, →ISSN, →OCLC:

     Plus: Cisco discloses a zero-day with no available patch, Venezuela accuses the US of a cyberattack, and more.

     (Can we archive this URL?)

2. A day without obligations, where one does not worry about being productive.
   • 2024 July 14, Christine Lehnen, “Why everyone should have ‘zero days’ and do the worst job first”, in The Guardian‎^[7], →ISSN:

     Whatever you do, do not cut out the “zero days” as suggested in Joel Snape’s article on productivity tips (Big, beautiful goals – but can’t be bothered? 11 great productivity tips for lazy people, 10 July). These are days where you have no obligations, where you do not worry about being productive.

References

• Hacker Lexicon: What Is a Zero Day? (on Wired.com)
• 0-day (zero-day) (on About.com)
• What is a Zero-Day Vulnerability? (on PCTools.com)

Anagrams

• zedoary