🚨 Next.js Security Alert 2026! 7 New Next.js Security Vulnerabilities Found — Is Your Next.js Project Safe?
On November 3, 2026, the Next.js team released an important **Next.js security update** addressing 7 security vulnerabilities. These Next.js vulnerabilities include cross-user cache data leaks, cache poisoning, HttpOnly cookie exposure, and other security risks affecting specific Next.js applications.
If you're using Next.js 15 or Next.js 16, you should check your Next.js version and review the latest security fixes.
In this video, we'll explore the **7 Next.js security vulnerabilities**, understand how these Next.js security issues can affect your application, and learn **how to fix Next.js vulnerabilities** by upgrading to patched versions.
🔥 **What You'll Learn in This Next.js Security Update:**
✅ What are the 7 new Next.js security vulnerabilities reported in November 2026?
✅ How does the Next.js Cross-Tenant Cache Data Leak work?
✅ How can one user's cached data become visible to another user in certain Next.js applications?
✅ What are the Next.js `use cache` and `unstable_cache` security issues?
✅ What do High and Medium security severity levels mean?
✅ Is your Next.js 15 or Next.js 16 project affected?
✅ How to check your current Next.js version.
✅ How to fix Next.js security vulnerabilities and protect your application.
✅ How to update Next.js to the available patched releases.
🛠️ **How to Fix Next.js Security Vulnerabilities**
**Step 1: Check Your Next.js Version**
Open your Next.js project terminal and run: `npm ls next`
**Step 3: Build and Test Your Next.js Application** `npm run build`
After updating Next.js, verify your application functionality, run your tests, and redeploy your updated Next.js project.
⚠️ **Important Next.js Security Note**
Not every Next.js project is affected by all 7 vulnerabilities. The actual security risk depends on your Next.js version, caching configuration, runtime, deployment environment, and the specific Next.js features your application uses.
If you use Next.js for production applications, keeping your Next.js dependencies updated is an important part of maintaining application security.
Welcome to Thapa Technical! Here you'll find practical tutorials, projects, and important developer updates covering JavaScript, React.js, Next.js, Node.js, Express.js, full-stack web development, and web application security.
This video warns Next.js developers about seven recently reported security vulnerabilities, including one high-severity bug. The most critical issue involves cross-tenant cache disclosure, where users from one organization could potentially access the cached data of another. The speaker provides a step-by-step guide on how to identify the current version and update to the latest patched version.
If you're using Next.js for your project, let me tell you
Why is it a very important security update for you?
Because just recently, only one day ago, on November 3,
Not one, not two, not three, on November 3, 2026.
A total of seven security vulnerabilities have been reported.
Among them, one is absolutely high severity, and the remaining six
They are medium severity bugs; one of these was such a bug.
Where, guys, cache data of one user, another user
What is your next application?
Is he really affected or not?
If it has happened, then how do we fix it now?
So let's not delay any further; let's start the video now.
And you can see that even Next.js's own team,
Which vulnerabilities exactly, okay?
Now, guys, out of these 7
An important issue has emerged.
What you need to know
And that's the very first one
This is the cross-tenant cache disclosure you are seeing
Let me explain it to you.
A simple example, brother
What problem was occurring due to this?
So let's suppose you are a
You're making the Next JS application,
Where users of multiple companies log in.
What should normal be like now?
Data from Company A is visible only to users of Company A.
Data from Company B is visible only to users of Company B.
But in Next.js, use cache function and unstable
when combining the scope cache in a particular way,
In certain specific situations, a company's cache
Data could have been accessible to users of another company.
And obviously this is a security concern.
You understand, guys, if a company's cached data is given to another
If the company's users can see it, then it's a risk, isn't it?
That was your previous one, similar to this total, and here the remaining 6
Yes, you will see it, but the most important thing right now is this
It is that brother, how do we fix this? This one is already done.
These are the two patches, so let me first inform you,
So come to your application, okay, so first of all, you need to make this
Make sure you know which version of Next.js is currently in your application.
If you're using this version, then the simplest way is this,
If you type npm ls next, you'll find out
Install Next, and then we have this at the rate 16.4.5
I'll have to update it.
How do I update now?
So, guys, this one is obviously right here.
You just sung it, copy it
Once it's copied, that's it, what else?
Then just hit enter, and boom
Your latest version will be installed.
and for some reason, if anyone is like this way
Running `npm ls next` does not show the version
So, just open your package.json file
Here you have it, nowhere else, next, all right, here we have a next,
Here you will find out which is the latest version of your next.
It's the one you've installed, okay, that's all you needed to do.
And by the way, not everyone necessarily has to be on version 16.
It might be on version 15, so if you are on version 15, then for you
copy paste enter this is it
Now guys, once you've completed the update, there's one important thing
Please run it once and show me all the functionalities you have.
Please take a good look to see whether they are working properly or not.
If you're not doing it, please check once
Which version did you update?
Nothing has been deprecated, or has any syntax changed for anyone?
Right, please make sure to do it
And once everything is going well for you
Then build it and redeploy it back.
So you've already fixed it locally here, but
It should be fine in production too, so then
You're all doing well, building and reading carefully.
Apply and don't get scared by this, this winning feeling
That's not the point, and another thing too: if you are righteous
That's enough for this video, please
This video is important, so all of you who have
Friends who work at Annex Jails
Definitely watch this video so that he can also get burned.
A new latest patch has arrived, and it's automatically updating itself.
