Yes, cloaking is a negative ranking factor, for both Google and Bing. If you show different content or URLs to humans and search engines, you’re cloaking. This is against Google’s guidelines and may result in a negative action against your website.

According to Google’s official documentation:

“Some examples of cloaking include:

– Serving a page of HTML text to search engines, while showing a page of images or Flash to users

– Inserting text or keywords into a page only when the User-agent requesting the page is a search engine, not a human visitor” source

Bing’s official statement is:

It should be noted that not all cloaking is spam related and we do our best to take this into account, however, we still don’t recommend cloaking in any situation). source