I am an undergraduate senior in CS looking to apply for software engineering internships for summer 2017. I also have plans to enroll in my school's one year CS MEng program after graduation, but acceptances don't come out until March. Will this disqualify me from internships that are looking for students who will be undergraduate/masters students after summer 2017? If possible, how can I express my future plans on my resume?
Generally assume requirements for anything are on the lenient side, whether the requirements are an exhaustive list of skills you do not have, more years of experience than you have been working, or a student status you ambiguously qualify for. Only the company can answer for sure and usually they ask for their ideal applicant, and widen the net as people inquire.
A resume is usually about completed accomplishments, not future plans. But, if you have finalized plans to begin a program, indicate it as: "X University Y program, expected completion 20xx." Your acceptance is, of course, an accomplishment and if you are willing to chain yourself to your future plan when you send your resume out, then you should include the program.
Your application should of course be transparent about your status but there is a little bit of an art to this. You have two responsibilities: making sure they are aware of your enthusiasm for the position, and making sure they are aware of your gray-area status so they can make a decision. Guess which one comes first?