How secure are extensions in browsers?

Golden said:

Can you explain how using this method would be any more secure, than from the normal user account? Surely a different user account doesn't mitigate any weakness in the browser?

Maybe I went a bit off topic, but my point was that even if we perfectly maintain our OS (security wise), you never know if what kind of a malware can be installed or is active on a user account which you use on daily basis, just by surfing internet (using a browser).

For example AV may not detect some malware yet.
I'm talking about malware which does not seek administrative privileges, it's only active in current account context for what ever purpose.

However if we switch to another user account (which is used only for banking), this potential malware can't do anything there, since that's now another user context, completely clean environment.

Assuming both accounts are non administrative, and there is no malware that has administrative privileges on system,
you are sure about that thanks to UAC. (subject to privilege escalation ofc. but...)

zebal said:

If you want to go one step forward and reduce the risk even more, you should consider doing banking on a separate windows account, which would be used only for transactions, purchases, banking etc..

I already use a user account and incognito mode which clears the cookies. What's the advantage a separate account for banking?

Steve C said:

I already use a user account and incognito mode which clears the cookies. What's the advantage a separate account for banking?

Hi Steve, I'm not sure if you've read my post above yours?

To expand on that post you can also take a read here:
Can I get a malware on Windows without administrative rights? - Information Security Stack Exchange

The malware can do everything your user is allowed to do.

The point is that on another windows account you have completely clean evironment, safe for banking.
Your Windows account which you use daily is not safe, even if your PC is completely clean.
And all this ofc. applies to browser extensions, and browsers them self.