It is known as a "zero-day" vulnerability because, effectively, it has been there since the product was launched - day zero - and not even its developer had spotted it.

该漏洞被称为“零日”漏洞，因为这一漏洞自从产品推出以来就一直存在——从第“零天”开始就存在，甚至连开发人员都没有发现过。

youdao

He claims that a zero-day vulnerability is found in every version of Internet Explorer for any version of Windows and allows hackers to hijack any cookie for any website.

他指出在windows平台所有版本的ie浏览器中都存在该零天攻击漏洞，该漏洞使黑客们可以窃取任何网站留下的cookie。

youdao

This vulnerability is published as a zero-day threat.

此漏洞作为零日威胁(zero - day threat)被公布。

youdao

This reduces the window of vulnerability during day zero of an attack.

FORBES: Why Most Companies Are Fighting The Wrong Security Battle

Hackers infected banner ads run by marketing firms such as Germany's Falk Esolutions, causing users who visited certain Web sites displaying Falk ads to download a Trojan horse that steals credit card numbers by exploiting yet another undetected vulnerability in Microsoft's Internet Explorer (a zero-day attack, once again).

FORBES: Criminal Outbreak

While some customers use this to overcome problems they have with enforcing vulnerability and patch management policies it is a cumbersome technology that does nothing to address new threats, zero day vulnerabilities, or insider attacks.

FORBES: Sophos + Astaro: Good companies, bad deal