There is provided a computer-implemented method for analyzing string-manipulating programs. An exemplary method comprises describing a string-manipulating program as a finite state transducer. The finite state transducer may be evaluated with a constraint solving methodology to determine whether a particular string may be provided as output by the string-manipulating program. The constraint solving methodology may involve the use of one or more satisfiability modulo theories (SMT) solvers. A determination may be made regarding whether the string-manipulating program may contain a potential security risk depending on whether the particular string may be provided as output by the string-manipulating program.