Whether or not you will be approved for a bridging loan with poor credit depends solely on your exit strategy. The lender will want to know as part of the application that you will be able to pay them back with no risk. If you provide security for your bridging loan, there is less of a risk to the lender overall, much like any other loan requiring collateral.
If your exit is selling your property to pay back your loan, this is a reliable source of income, which may improve your chances even if you have poor credit. But if you are relying on a remortgage for finance, you may find that lenders cannot provide you with the loan you need due to a poor credit rating. A poor credit rating may not be a problem for bridging loans specifically, but if your exit is affected by your financial history, this may prove an issue during your application.