zero-day vulnerability

Syllable breakdown

Dictionary meaning

a software security flaw that is unknown to the vendor or developer and therefore has no available patch or mitigation at the time it is discovered or exploited; the term zero-day refers to the fact that developers have had zero days to address and fix the vulnerability before it can be weaponised; zero-day vulnerabilities are among the most dangerous and valuable assets in offensive cybersecurity, traded on grey and black markets for significant sums and weaponised by nation-state threat actors and criminal organisations against high-value targets