Zero-Day Vulnerabilities: Live Threat Intelligence
Track zero-day vulnerabilities and actively exploited flaws as they are disclosed, with analysis of the risk and how to respond.
A zero-day is a vulnerability that attackers exploit before the vendor has released a patch — leaving defenders with no fix to apply, only mitigations. Because of that, zero-days are among the most dangerous threats in cybersecurity and are highly prized by sophisticated adversaries. This page aggregates reporting on zero-days and actively exploited vulnerabilities from authoritative sources in real time.
Why zero-days are so dangerous
The danger of a zero-day lies in the window between exploitation and patching. During this period, signature-based defenses often miss the novel exploit, and a reliable zero-day in widely used software can give attackers access to thousands of organizations before anyone notices. A working exploit for a popular platform can command very high prices on both legitimate bug-bounty programs and gray markets, fueling a whole economy of discovery and resale.
Zero-days vs known vulnerabilities
While zero-days dominate headlines, it is worth keeping perspective: the majority of breaches actually exploit known vulnerabilities for which a patch already existed but had not been applied. The most dangerous moment is when a flaw is being actively exploited but unpatched — a situation that authorities like CISA flag with urgent advisories and add to the Known Exploited Vulnerabilities (KEV) catalog. When a patch does land, attackers race to exploit it against organizations slow to update.
What to watch
- CISA KEV additions — confirmed in-the-wild exploitation; patch these first.
- Emergency vendor advisories — out-of-band patches usually signal active exploitation.
- Internet-facing products — VPNs, firewalls, email gateways and management interfaces are favorite zero-day targets because exploitation requires no user interaction.
How to defend against zero-days
You cannot patch a flaw nobody knows about, but you can limit the blast radius: practice defense in depth, deploy behavior-based detection that catches malicious activity rather than known signatures, apply least privilege and segmentation, use virtual patching (WAF/IPS) while awaiting fixes, and — above all — patch known vulnerabilities rapidly to close the much larger n-day window. Our guide explains zero-day vulnerabilities, exploits and attacks in depth, and our CVSS vs EPSS guide covers prioritization.
Speed of awareness is everything with zero-days. The live feed below surfaces actively exploited and zero-day reporting as it breaks.