Zero-day attacks have become one of the biggest security problems in 2025. A zero-day is a flaw attackers find before the company even knows it exists, and a zero-day vulnerability is the specific weakness they exploit while there’s still no patch. This year, the problem has grown fast. Roughly 40 percent of the entries added to CISA’s Known Exploited Vulnerabilities list are zero-days, and security teams say attackers now weaponize new vulnerabilities in five days or less once they’re discovered. It puts organizations under constant pressure because these flaws hit the tools people rely on every day, from Microsoft Word and Apple iMessage to Chrome, Oracle EBS and major enterprise systems.

TL;DR

The year saw 15 major zero-days across Microsoft Word, SharePoint, Windows Kerberos, Apple iMessage, Core Media, Chrome GPU, Oracle EBS, Redis, GoAnywhere MFT, Android media codecs and Cisco IOS XE. Most of them allowed remote code execution or privilege escalation. If you use these systems, patch them as soon as updates land and monitor your devices closely.

Top 15 Zero Day Vulnerabilities in 2025

Here’s a clean, platform-wise table showing the CVE (where available), the affected component and what attackers could do with it.

Top 15 Zero-Day Vulnerabilities 2025 (Table)

Why These Zero-Days Matter

These vulnerabilities hit the most popular systems in the world. Many of them allowed attackers to run code, break device security, steal data or gain high-level access. Some were used before vendors even confirmed the flaw. When critical platforms like Word, iMessage, Chrome, Oracle ERP or Cisco IOS XE get affected, the impact spreads fast because millions of people use them daily.

To stay safer:

• Update your devices and servers on time
  
• Turn on multi-factor authentication
  
• Watch for strange login attempts
  
• Patch older on-prem systems quickly
  
• Monitor your network for unexpected commands or file activity
  

Even one ignored update can turn into a major security incident.

To Sum Up

The top zero day vulnerabilities 2025 show how fast attackers are moving and how quickly flaws are being exploited. These weaknesses affected almost every major platform we use today, from Microsoft and Apple devices to Oracle ERP systems, browsers, Android and even network equipment. The best way to stay ahead is to keep your systems updated, watch for strange activity and use layered security. Since many readers may still have questions about how zero-days work or what to do next, the FAQs below offer simple answers.

FAQs on Zero-Day Vulnerabilities in 2025

1. What exactly is a zero-day vulnerability?

A zero-day vulnerability is a flaw that attackers find before the company knows it exists. There’s no patch, no fix and no warning. Attackers can break in while defenders have zero days to prepare.

2. Why are zero-day attacks increasing in 2025?

Attackers are moving faster, and many platforms are more connected than before. Analysts say weaponization now happens in five days or less, giving very little time to respond.

3. Why do the top zero day vulnerabilities 2025 matter so much?

They target everyday tools like Microsoft Word, SharePoint, iMessage, Chrome, Oracle ERP, Android and Cisco devices. These systems run everywhere. One unpatched flaw can lead to data theft, ransomware or full network compromise.

4. How are zero-day vulnerabilities different from regular vulnerabilities?

Regular vulnerabilities have patches or known workarounds. Zero-days don’t. Attackers exploit them before vendors confirm the flaw.

5. Who is most at risk from zero-day attacks?

Everyone, but especially:

• Businesses running old on-prem systems
  
• Organizations with slow patching cycles
  
• High-value sectors like finance, healthcare and government
  
• People using outdated browsers or devices
  

6. How can I reduce the risk of a zero-day attack?

You can’t stop zero-days from appearing, but you can limit the damage:

• Update devices quickly
  
• Turn on MFA
  
• Limit admin rights
  
• Monitor accounts and network activity
  
• Use EDR/XDR tools
  
• Segment your network
  

7. What should small businesses focus on if they can’t track every CVE?

Simple steps go a long way:

• Automatic updates
  
• Strong passwords and MFA
  
• Good endpoint security
  
• Regular data backups
  
• Email and messaging protection
  
• Working with a trusted IT partner
  

8. Which platforms saw the worst zero-days in 2025?

The biggest hits were seen in:

• Microsoft (Word, SharePoint, Kerberos, Win32k)
  
• Apple (iMessage, Core Media, Safari WebKit)
  
• Chrome and WebKit browsers
  
• Oracle EBS
  
• GoAnywhere MFT
  
• Redis
  
• Cisco IOS XE
  
• Android media components