In Chrome, extensions are sandboxed using similar technique as web pages are.
However, just because they are sandboxed doesn't mean they are safe. It just means they won't be able to get privileges beyond those explicitly granted to them.
Many extensions request very powerful privileges though, like the ability to read and write to web pages you visit. The browser will dutifully grant this privilege if the extension requests it and you allow it. It won't get the ability to run arbitrary native code though (unless it also requests that privilege).
In Chrome, extensions are sandboxed using similar technique as web pages are.
However, just because they are sandboxed doesn't mean they are safe. It just means they won't be able to get privileges beyond those explicitly granted to them.
Many extensions request very powerful privileges though, like the ability to read and write to web pages you visit. The browser will dutifully grant this privilege if the extension requests it and you allow it. It won't get the ability to run arbitrary native code though (unless it also requests that privilege).