A method may include determining that a non-constant value of a variable corresponding to a variable node of the abstract syntax tree flows into an operator node in the abstract syntax tree. The method may further include adding, to the abstract syntax tree, a check taint node including functionality to: make a taint status determination that the non-constant value is tainted, and return the non-constant value to the operator node. The operator node generates a result value by executing an operator using the non-constant value. The method may further include adding, to the abstract syntax tree, a set taint node that stores, based on the taint status determination, the result value in a second tainted object, and performing, using the abstract syntax tree, a taint analysis of the source code to identify a vulnerability in the source code.