The amount of vulnerabilities in soft-
ware grows everyday. This report ex-
amines vulnerabilities in Flask web
applications, which is a Python web
framework. Cross site scripting, com-
mand injection, SQL injection and path
traversal attacks are used as example
vulnerabilities. A static analysis of
Python is used to analyse the flow of
information in the given program. The
static analysis consists of constructing
a control flow graph using polyvariant
interprocedural analysis. The fixed-
point theorem is used for analysing
the control flow graph. Using an ex-
tended version of the reaching defi-
nitions it is possible to capture infor-
mation flow through a program. A
tool has been implemented and can be
used on whole projects giving possi-
ble vulnerabilities as output. At last an
evaluation of the tool is presented. All
example vulnerabilities were detected
and real world projects were success-
fully used as input.