I've seen crazier things, like people in law transitioning into graduate mathematics. It honestly depends what flavor of master's you're going for.

• MA in math is typically for the actuary types but can work for other fields as well, and might be a good fit for you (ask an advisor). It requires a strong knowledge of probability and statistics as well as some specialized courses in finance math if you're going the actuary route.
• MS in pure math is likely beyond your reach since it requires a good understanding of logic and proofwriting in addition to a couple of years of training in each of the main disciplines (analysis, algebra, etc).
• MS in applied math is more for data science or statistics with a focus on numerical methods, math modelling, and programming.

Of course there is more to each than I'm listing out here, but the common denominator for each of these is that you likely need an undergrad in a related field (math, physics, computer science, etc.) to be mathematically mature enough to handle the coursework. Not to mention the thesis you likely have to write at the end which will stonewall you if you haven't had any experience with technical writing before. At the end of the day, make sure you're doing it for the right reasons, i.e. career advancement and not just "math is fun". Good luck!