Some Chrome extensions have permission to 'access data on all websites'. Is the LastPass Vault safe?
Yes, your data is safe in the Vault. The local* Vault is a chrome-extension:// page, which is not a webpage, so other extensions cannot access it. While in the online** Vault , passwords remain encrypted until you need to use them.
However, your passwords are vulnerable when they leave LastPass to autofill on a site. Once autofilled, the password is now on a website and could potentially be grabbed. We recommend that you only use extensions that you trust.
For a great explanation on these permissions and when you should be weary, please see Lifehacker's article, Why Do Chrome Extensions Need to Access All My Data.
*Local Vault URL: chrome-extension://hdokiejnpimakedhajhdlcegeplioahd/homelocal2.html
**Online Vault URL: https://lastpass.com/?ac=1