[duskwuff]

No, there's a worse attack possible: you can attempt to include a resource with sensitive contents with SRI, and use the SRI to make a "guess" at the hash of the contents. If your guess is incorrect, the resource will fail to load, and you can detect this error and make another guess.

Obviously, this technique will only work if the contents of that resource are constrained enough that it's possible to guess them with brute force. Depending on how SRI interacts with the browser cache, though, it may be possible to make guesses very quickly -- it is likely that the browser will only fire one HTTP request for the initial attempt, and will load the resource from cache for all subsequent attempts.