You installed a browser extension that promised to summarize pages, draft emails, or answer questions about whatever you are reading. It sits in a neat side panel and feels harmless. Then you notice a permission prompt that says it can "read and change all your data on all websites," and you wonder what that actually means for the bank login, the client spreadsheet, or the draft contract open in another tab.
That worry is justified. Browser extensions have some of the most powerful access on your machine, often more than the websites you visit. Security researchers have repeatedly found extensions that quietly harvested page content, injected ads, or were sold to new owners who changed their behavior. In a widely cited 2023 analysis of the Chrome Web Store, researchers identified large numbers of extensions requesting broad host permissions that were far wider than their stated function required. Many users never looked at the permission list at all.
This article explains what browser extension permissions actually are, what an AI side panel can read in practice, and how to check before you trust one. You will get a worked example with real numbers, a comparison of permission models across common browsers and extension types, and a numbered audit process you can run in about ten minutes. We will also cover where the risks are overstated and where they are genuinely serious.
Key Takeaways
- A permission like "Read and change all your data on all websites" lets an extension read the content of nearly every page you load, including logged-in pages.
- AI side panels usually need page content access to be useful, so the real question is which sites, when, and where the data goes.
- Prefer "on click" or "on specific sites" access over "all sites" whenever the extension allows it.
- Permissions tell you the ceiling of what is possible, not what is happening. Check the privacy policy and network behavior too.
- Audit extensions the same way you audit passwords: list them, count their reach, remove what you do not use, and re-check after every update.
What Browser Extension Permissions Actually Mean
Browser extension permissions are the access rights an extension requests from the browser before it can interact with your data, your tabs, or the web. The browser displays them at install time, and the extension's manifest file records exactly which ones it has declared. Permissions are the gatekeeping layer between an extension's code and the sensitive parts of your browsing.
Most permissions fall into a few categories:
- Host permissions: which websites the extension can read from and write to. This is the most important category for AI tools.
- API permissions: access to browser features such as
tabs(see your open tab titles and URLs),storage(save data locally),cookies,history,bookmarks, ordownloads. - Content scripts: JavaScript injected into web pages, which can read and modify the page's DOM. Any extension with content scripts on a site can see what is rendered there.
- Network access: the ability to send requests to external servers. This is where data leaves your machine.
A permission is a capability, not a behavior. An extension with "all sites" access could read every page and never does. Another with narrow access could still leak what it reads. Treat permissions as the outer boundary and verify inside it.
Why AI side panels request so much access
An AI side panel is only useful if it knows what you are looking at. To summarize an article, it needs the article text. To answer a question about a product page, it needs the page. To help you draft a reply inside a webmail client, it needs to read the thread. That makes broad host access a functional requirement for most of these tools, not a sign of bad intent.
The problem is that the same access that makes the tool useful also means it can see your banking dashboard, your health portal, your company's internal wiki, and your email. Developers often request "all sites" because it is easier than asking per domain, and because users tend to accept whatever the install dialog shows.
What an AI Side Panel Can Read in Practice
When people ask whether an AI extension can "read my data," they usually mean three different things. Separating them makes the risk much easier to judge.
Page content
With a content script running on a site, the extension can read the visible text, form fields, and often the hidden DOM. That includes what you typed into an unsent email draft, the account balance on a logged-in banking page, or the patient name on a portal. Form inputs are readable even when you have not submitted them, which is why a single "all sites" grant can expose far more than the pages you meant to share.
Browsing metadata
With the tabs or history permission, the extension can see the URLs and titles of your open and past tabs. Even without reading page bodies, a list of URLs reveals your employer's internal tool names, medical providers, legal case pages, and private search queries embedded in URLs.
Stored data and session state
Extensions with cookies access or the ability to inject scripts into authenticated pages can, in principle, act within your logged-in sessions. Most reputable AI tools do not do this, but the permission exists and would be enough for a malicious version.
A worked example: 47 passwords, 12 services, one extension
Consider a freelance consultant, Maya, who runs her work through 12 online services: email, calendar, two cloud drives, a CRM, invoicing, a bank portal, a tax filing site, a project board, a client portal, a password manager web vault, a payroll dashboard, and a social media scheduler. Between them she has 47 separate passwords and sessions that stay logged in for days.
She installs an AI side panel extension with the permission "Read and change all your data on all websites." Here is what that single grant means for her:
- The extension can run a content script on all 12 services, meaning it can read page content on each once she loads them.
- It can see the URLs of all her open tabs, which reveal the names of her clients (in CRM and invoice URLs) and her bank.
- If the extension sends any page content to its servers, then the body text of her invoices, client emails, and payroll figures could leave her machine. Her 47 passwords are not directly readable from page content, but session tokens in the page or the ability to act within authenticated sessions is the bigger concern.
- Her realistic exposure: 12 of 12 services, every session, every day she uses the browser.
Now apply a narrower model. Maya configures the same tool to run "on click" only, or restricts it to two domains: her CRM and her project board. Her exposure drops from 12 services to 2, and only when she actively invokes the panel. The tool still works for the tasks she cares about, and the number of places her financial and client data can be read falls by more than 80 percent. That gap is the entire point of permission hygiene.
Permission Models Compared: Which Setup Fits Your Risk
Not every browser or extension handles permissions the same way. The table below compares common access models you will encounter.
| Access model | Where it appears | What the extension can read | User control | Typical risk level | Best for |
|---|---|---|---|---|---|
| All sites, always on | Many AI side panels, ad blockers, grammar tools | Every page you load, all the time | Low unless you revoke manually | High | Users who accept broad reach for convenience |
| Specific sites only | Chrome and Edge site access settings, Firefox per-site controls | Only listed domains | High | Medium to low | Users with a clear list of trusted work sites |
| On click / activeTab | Chrome activeTab model, many summarizers |
Current tab only, only after you click | High | Low | Occasional summarization, reading articles |
| Sidebar with page context on demand | Newer AI browsers and panel extensions | Page content only when you send it | High | Low | Users who want AI help without ambient reading |
| Native browser AI (no extension) | Built-in assistants in some browsers | Governed by browser's own privacy terms | Medium | Depends on provider | Users who trust one large vendor's policy |
A practical rule: if the task is one page at a time, choose on-click. If the task is a recurring workflow on a few sites, choose specific-site access. Reserve all-sites access for tools you have audited and use daily, and even then, review it quarterly.
How to Audit an Extension's Permissions in 10 Minutes
You do not need specialist tools to do a meaningful review. The following process works in Chrome, Edge, Brave, and most Chromium-based browsers, with minor menu differences. Firefox users can follow the same logic using the Add-ons Manager.
- Open the extensions page. Type
chrome://extensions(oredge://extensions) in the address bar. Turn on Developer mode if you want the extension ID and manifest details. - List everything. Write down every extension you have installed. Most people discover three to five they forgot about. Note which ones you actually used in the last 30 days.
- Remove the unused ones. Any extension unused for 30 days with broad access is a candidate for removal. You can always reinstall.
- Open "Details" for each remaining extension. Look at the "Site access" setting. Options typically read "On click," "On specific sites," or "On all sites." Record which one applies.
- Switch to the narrowest setting that still works. If an extension is set to "all sites" but you only use it on two domains, change it to "on specific sites" and add those domains.
- Read the permission list. Click "Permissions" in the extension details, or view the install dialog again on the Chrome Web Store listing. Flag anything beyond what the tool's description needs, such as
history,cookies,downloads, ornativeMessaging. - Check the publisher and recent changes. Look at when the extension was last updated, whether the publisher changed recently, and whether the listing has a privacy policy. A sudden ownership change followed by new permissions is a classic warning sign.
- Read the data handling section. Find out whether page content is sent to external servers, whether it is used for training, and how long it is retained. If the policy is vague about any of these, assume the worst case for sensitive sites.
- Test on a non-sensitive page first. Run the tool on a public article and watch the behavior. Use your browser's developer tools (Network tab) to see whether outbound requests carry page text.
- Calendar a re-check. Extensions update silently and can expand permissions in new versions. Re-check this list every quarter, and whenever a new permission
