Does this apply to a project released under Apache 2.0 with no additional CLA?
Yes, submissions to an Apache 2.0 licensed project are themselves Apache 2.0 licensed. From section 5 of the license text:
5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions.