A zero-day vulnerability refers to a security flaw in software, hardware, or firmware that is unknown to the party responsible for fixing it, typically the vendor. Since the vulnerability is not yet known to the developer or the public, attackers can exploit it before a patch or fix is developed and released. This makes zero-day vulnerabilities particularly dangerous because there is no immediate defense against them.
Here’s a breakdown:
- “Zero-day” means there is zero time between when the vulnerability is discovered and when it’s exploited.
- Exploitation of these vulnerabilities is often referred to as a “zero-day attack.”
- Patching or fixing the vulnerability can only occur once it’s discovered and reported, which can take some time depending on the complexity of the issue.
- Targets of zero-day attacks can include operating systems, browsers, applications, or any system with software flaws.
Because these vulnerabilities are unknown, they are often sold on the black market to malicious actors or governments and can be used in cyber espionage, data breaches, or to gain unauthorized access to systems.