What Are Internet Cookies, and Are They a Security Risk?

Summary: Internet cookies are small text files your browser stores to remember your login, preferences, and shopping cart. Most are harmless. But in 2026, stolen session cookies have become a serious cybersecurity threat, capable of bypassing passwords and two-factor authentication. Here’s what you need to know. 

If you’ve visited a website lately, you’ve probably been asked to click “Accept” or “Reject” on a cookie notice. Sites used to handle this quietly in the background. Now they’re required to ask. Most people click accept without thinking twice, especially since some sites won’t work properly without cookies enabled. 

That reflex is mostly harmless. Cookies themselves are a fundamental part of how the web works. They’re small text files your browser stores so websites can remember you between visits. Your login, your shopping cart, your language settings cookies are what keep all of that intact. 

Quick Answer: What are internet cookies? Internet cookies are small text files your browser stores to remember you — your login, preferences, and shopping cart — so websites can recognize you on return visits. They’re generally safe, but stolen session cookies have become a major cybersecurity threat in 2026, enabling hackers to bypass passwords and even two-factor authentication to access your accounts.

What are Cookies? 

Internet cookies are small text files your browser stores to remember you, like your login, preferences, and shopping cart, so websites can recognize you on return visits. They’re generally safe, but stolen session cookies have become a major cybersecurity threat in 2026, enabling hackers to bypass passwords and even two-factor authentication to access your accounts. Cookies are created by the web server when you connect to a site and labeled with an ID unique to your device. That ID is what allows the server to recognize you the next time you return, so it can pull up your preferences, keep you logged in, or restore your shopping cart without making you start over. Think of cookies as the Cheers of the internet: they know your name and greet you with a warm welcome.

 

What Kinds of Cookies Exist? 

There are two types of cookies: single-session cookies and persistent cookies (also called multi-session cookies). 

Single-session cookies are used to: 

• Help with website navigation 

• Temporarily record information that gets erased when the browser is closed 

• Provide the smoothest navigation experience possible (that’s why they’re automatically enabled) 

Persistent cookies: 

• Remain on your computer and record information every time you visit the site 

• Are stored on your device’s hard drive until you manually delete them. Some cookies will expire, but that can be years after they were created 

• Provide analysis of site use and to maintain access quality (think things like your theme settings, bookmarks, and language preferences) 

Single- and multi-session cookies work together to make your internet experience as seamless as possible. After all, it’d be annoying to have to manually select the same settings every single time you return to a site. 

Where are Cookies Stored? 

The cookies that are created are stored locally in your browser (y’know, instead of locally on your kitchen counter in a cookie jar). If you return to that site later, your browser shows the saved data to the web server as a cookie. What it’s actually doing is recalling data from your previous sessions (like anything you may have left in a cart while online shopping) and restoring that information. Handy if you order the same thing every week for lunch, right? 

What are Internet Cookies Used For? 

Cookies are primarily used for three things. 

• Session management: includes things like keeping you logged in to accounts and remembering your preferences 

• Personalization: the main way you experience this is custom advertising. If you view certain items or areas of a website, cookies use that data to build targeted ads for products you’re more likely to buy 

• Tracking: shopping sites use cookies to track the items you previously viewed, which allows them to suggest other items you might like, and store items in your shopping cart while you keep browsing 

Clearly, when cookies work correctly, they make our online lives easier and more tailored to our taste. But what happens if they don’t work correctly? Can bad cookies burn the consumer? 

Are Cookies a Security Risk? 

Cookies themselves aren’t harmful, but cookie theft has become one of the fastest-growing cybersecurity threats of 2026. 

Researchers have found 94 billion stolen browser cookies circulating on the dark web, harvested by at least 38 different malware strains, a 74% surge from the prior year. More than 20% of those cookies are still active, meaning they can be used right now to access real accounts. 

What makes this especially alarming is that stolen session cookies can bypass multi-factor authentication (MFA). Many websites skip the MFA check for returning users who have a valid session cookie, particularly “Remember Me” tokens. If a hacker steals that token, they can log into your accounts without ever knowing your password or triggering a 2FA prompt. The FBI specifically warned about this attack method in late 2024. 

There are three main sources of cookies to understand: 

First-party cookies are created by the site you’re visiting. These are generally safe, as long as you’re sticking to reputable websites. 

Third-party cookies are set by domains other than the site you’re on, typically advertisers or analytics providers embedded in the page. Even if you don’t click on an ad, visiting a page with five embedded ads can result in five third-party cookies. Advertisers can then track your browsing across any site that runs their code. It’s worth noting that as of 2026, Safari and Firefox already block third-party cookies by default. 

Zombie cookies (also called flash cookies) are a particularly stubborn variety. They’re designed to re-create themselves after you delete them by using backup copies stored outside the browser’s normal cookie folder. To remove them, you’ll need to go beyond standard cookie clearing. Browser developer tools, a privacy-focused extension like uBlock Origin, or a dedicated privacy cleaner can help locate and remove them. 

Should You Remove Cookies? 

Even if you don’t have “bad” cookies on your device, it’s still a good idea to periodically remove them to minimize your risks of privacy breaches.

How to Delete Cookies (By Browser) 

Clearing cookies takes less than a minute in any major browser. Here’s how to do it in each one. 

Google Chrome 

1. Open Chrome and click the three-dot menu in the top-right corner. 

1. Select Settings > Privacy and security > Delete browsing data. 

1. Check Cookies and other site data, choose your time range, and click Delete data. 

Mozilla Firefox 

1. Click the three-line menu in the top-right corner. 

1. Select Settings > Privacy & Security. 

1. Under Cookies and Site Data, click Clear Data, check Cookies and Site Data, and click Clear. 

 

Apple Safari (Mac) 

1. Open Safari and click Safari in the menu bar, then Settings. 

1. Go to the Privacy tab and click on Manage Website Data. 

1. Click Remove All or select individual sites to remove. 

 

 Microsoft Edge 

1. Click the three-dot menu in the top-right corner. 

1. Select Settings > Privacy, search, and services. 

1. Under Clear browsing data, click Choose what to clear, check Cookies and other site data, and click Clear now. 

 

On iPhone (Safari) 

1. Open the Settings app and scroll to Apps, then tap Safari. 

1. Tap Clear History and Website Data. 

1. Choose a time range and tap Clear History. 

 

 On Android (Chrome) 

1. Open Chrome and tap the three-dot menu. 

1. Tap Privacy and security > Clear browsing data. 

1. Check Cookies and site data and tap Delete data. 

 

Note: Clearing cookies will log you out of most websites and reset saved preferences like language or theme settings. It’s a good habit to do this every month or two as part of your regular digital hygiene, not something you need to do daily. 

Do VPNs Protect You from Cookie Tracking? 

A VPN is a useful privacy tool, but it doesn’t block or delete cookies. VPNs encrypt your connection and mask your IP address, which helps while on public Wi-Fi and limits what your ISP can see, but websites still set and read cookies in your browser regardless of whether you’re using one. 

For actual cookie protection, your best combination is adjusting your browser’s cookie settings, clearing cookies regularly, and using a tracker-blocking extension like uBlock Origin. Add a VPN on top of that for broader privacy coverage, and you’re in good shape. 

Cookies are one of the building blocks of your personalized internet experience, and for the most part, they work quietly in your favor. But understanding the difference between harmless session cookies and the tracking or security risks posed by third-party and stolen cookies puts you in a much stronger position. Clearing your cookies regularly, reviewing your browser’s privacy settings, and using a VPN for additional IP-level protection are all meaningful steps toward a safer, more private browsing experience.