Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues
Project coverage

Table of contents

Project overview: flask-restx
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: fuzz_reqparse
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Fuzz engine guidance
/src/fuzz_reqparse.py
Dictionary
Fuzzer function priority
Runtime coverage analysis
Complex functions with low coverage
Files and Directories in report
Files in report
Directories in report
Metadata section
Report generation date: 2025-07-11

Project overview: flask-restx

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
3.0%
44 / 1625
Cyclomatic complexity statically reachable by fuzzers
3.0%
176 / 5557
Runtime code coverage of functions
24.0%
384 / 1625

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_reqparse /src/fuzz_reqparse.py 134 2896 7 16 116 443 fuzz_reqparse.py

Project functions overview

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name Functions filename Args Function call depth Reached by Fuzzers Runtime reached by Fuzzers Combined reached by Fuzzers Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Fuzzer details

Fuzzer: fuzz_reqparse

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The distribution of callsites in terms of coloring is
Color Runtime hitcount Callsite count Percentage
red 0 173 70.0%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 74 29.9%
All colors 247 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
58 38 werkzeug.test.EnvironBuilder.get_request call site: 00038 werkzeug.test.stream_encode_multipart
42 137 flask.ctx.AppContext.__init__ call site: 00137 werkzeug.routing.map.Map.bind_to_environ
20 16 werkzeug.test.EnvironBuilder.__init__ call site: 00016 werkzeug.test._iter_data
8 190 flask_restx.reqparse.Argument.source call site: 00190 werkzeug.datastructures.structures.MultiDict.__init__
8 200 werkzeug.datastructures.structures.MultiDict.__init__ call site: 00200 werkzeug.datastructures.structures.CombinedMultiDict.lists
5 239 flask_restx.reqparse.RequestParser.parse_args call site: 00239 flask_restx.errors.abort
4 126 werkzeug._internal._wsgi_decoding_dance call site: 00126 werkzeug._internal._wsgi_decoding_dance
3 117 werkzeug.wrappers.request.Request.__init__ call site: 00117 werkzeug.wsgi._get_server
3 215 werkzeug.datastructures.structures.MultiDict.items call site: 00215 .isinstance
2 97 werkzeug.urls._urlencode call site: 00097 .len
2 123 werkzeug.wsgi._get_server call site: 00123 werkzeug._internal._wsgi_decoding_dance
2 187 ...fuzz_reqparse.TestOneInput call site: 00187 flask_restx.reqparse.Argument.source

Runtime coverage analysis

Covered functions
496
Functions that are reachable but not covered
105
Reachable functions
134
Percentage of reachable functions covered
21.64%
NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.
Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.
Function name source code lines source lines hit percentage hit

Files reached

filename functions hit
/ 1
...fuzz_reqparse 9
werkzeug.wrappers.request 8
werkzeug.test 44
werkzeug.urls 5
werkzeug.sansio.multipart 6
werkzeug._internal 8
werkzeug.wsgi 4
werkzeug.datastructures.headers 1
flask.app 4
flask.ctx 1
werkzeug.sansio.utils 7
werkzeug.routing.map 19
flask_restx.reqparse 15
werkzeug.datastructures.structures 21
flask_restx.errors 2

Analyses and suggestions

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name Functions filename Arg count Args Function depth hitcount instr count bb count cyclomatic complexity Reachable functions Incoming references total cyclomatic complexity Unreached complexity
werkzeug.debug.DebuggedApplication.__call__ werkzeug.debug 3 ['N/A', 'N/A', 'N/A'] 7 0 1 6 5 237 0 783 691
flask_restx.swagger.Swagger.as_dict flask_restx.swagger 1 ['N/A'] 5 0 2 9 7 95 1 327 279
flask.app.Flask.wsgi_app flask.app 3 ['N/A', 'N/A', 'N/A'] 7 0 5 2 4 128 1 439 266
flask.app.Flask.run flask.app 6 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 4 0 8 10 7 108 0 348 234
werkzeug.test.Client.resolve_redirect werkzeug.test 3 ['N/A', 'N/A', 'N/A'] 7 0 3 8 6 153 10 511 211
werkzeug.formparser.FormDataParser.parse werkzeug.formparser 5 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 6 0 1 4 5 76 2 257 196
werkzeug.wrappers.response.Response.make_conditional werkzeug.wrappers.response 4 ['N/A', 'N/A', 'N/A', 'N/A'] 10 0 1 6 5 77 0 260 161

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers
16.0%
264 / 1625
Cyclomatic complexity statically reachable by fuzzers
19.0%
1062 / 5557

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name Functions filename Args Function call depth Reached by Fuzzers Runtime reached by Fuzzers Combined reached by Fuzzers Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Fuzz engine guidance

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

/src/fuzz_reqparse.py

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name 

-focus_function=['werkzeug.test.EnvironBuilder.get_request', 'flask.ctx.AppContext.__init__', 'werkzeug.test.EnvironBuilder.__init__', 'flask_restx.reqparse.Argument.source', 'werkzeug.datastructures.structures.MultiDict.__init__', 'flask_restx.reqparse.RequestParser.parse_args', 'werkzeug._internal._wsgi_decoding_dance', 'werkzeug.wrappers.request.Request.__init__', 'werkzeug.datastructures.structures.MultiDict.items', 'werkzeug.urls._urlencode']

Runtime coverage analysis

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name Function total lines Lines covered at runtime percentage covered Reached by fuzzers
flask.app.Flask.run 31 0 0.0% []
flask.app.Flask.make_response 33 0 0.0% []
flask_restx.reqparse.Argument.parse 48 26 54.16% ['fuzz_reqparse']
werkzeug.wsgi.LimitedStream.readinto 32 0 0.0% []
werkzeug.test.stream_encode_multipart.write_binary 41 0 0.0% ['fuzz_reqparse']
werkzeug.test.EnvironBuilder.__init__ 63 33 52.38% ['fuzz_reqparse']
werkzeug.test.Client.open 34 0 0.0% []
werkzeug.test.run_wsgi_app.start_response 32 8 25.0% ['fuzz_reqparse']
werkzeug.formparser.MultiPartParser.parse 33 0 0.0% []
r.as_dict 251 49 19.52% ['fuzz_reqparse']
werkzeug.utils.send_file 81 0 0.0% []
sources.append 1640 2 0.121% ['fuzz_reqparse']
time.sleep 78 14 17.94% ['fuzz_reqparse']
werkzeug.sansio.multipart.MultipartDecoder.next_event 50 0 0.0% []
werkzeug.http.parse_options_header 57 12 21.05% ['fuzz_reqparse']
werkzeug.http.parse_range_header 40 0 0.0% []
werkzeug.http.dump_cookie 34 0 0.0% []
re.match 1212 375 30.94% ['fuzz_reqparse']
markupsafe.escape.splitlines 182 73 40.10% ['fuzz_reqparse']
flask.cli.find_app_by_string 34 0 0.0% []
flask.cli.routes_command 32 1 3.125% ['fuzz_reqparse']
werkzeug.routing.map.MapAdapter.match 32 0 0.0% []
werkzeug.serving.WSGIRequestHandler.make_environ 35 0 0.0% []
werkzeug.serving.WSGIRequestHandler.run_wsgi.execute 40 0 0.0% []
werkzeug.serving.BaseWSGIServer.__init__ 45 0 0.0% []
o.__html__ 38 16 42.10% ['fuzz_reqparse']
val.lower 146 16 10.95% ['fuzz_reqparse']
werkzeug.routing.matcher.StateMachineMatcher.match._match 74 0 0.0% []
flask.sansio.blueprints.Blueprint.register 49 0 0.0% []
types.MethodType 438 174 39.72% ['fuzz_reqparse']
flask_restx.api.Api.__init__ 43 0 0.0% []
flask_restx.api.Api.handle_error 49 0 0.0% []
flask_restx.swagger.Swagger.as_dict 33 0 0.0% []
flask_restx.swagger.Swagger.extract_resource_doc 42 0 0.0% []
flask_restx.swagger.Swagger.responses_for 42 0 0.0% []
p.get 53 9 16.98% ['fuzz_reqparse']
flask_restx.inputs.URL.__call__ 46 0 0.0% []

Files and Directories in report

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file Reached by Covered by
[] []
hmac [] []
werkzeug.datastructures.range [] []
code [] []
traceback [] []
base64 [] []
socketserver [] []
blinker [] []
flask.testing [] []
uuid [] []
atheris [] []
flask.blueprints [] []
flask_restx.__about__ [] []
ast [] []
werkzeug.routing.converters [] []
werkzeug.datastructures.structures ['fuzz_reqparse'] []
flask_restx._http [] []
werkzeug.middleware.shared_data [] []
cryptography [] []
flask.__main__ [] []
pprint [] []
werkzeug.wrappers [] []
flask_restx.representations [] []
importlib_resources [] []
werkzeug.debug [] []
werkzeug.middleware.lint [] []
sys [] []
werkzeug.middleware.http_proxy [] []
fnmatch [] []
werkzeug.sansio.utils ['fuzz_reqparse'] []
mimetypes [] []
typing [] []
werkzeug._reloader [] []
flask.templating [] []
flask.debughelpers [] []
cProfile [] []
textwrap [] []
werkzeug.routing.map ['fuzz_reqparse'] []
zlib [] []
werkzeug.middleware.dispatcher [] []
itertools [] []
linecache [] []
werkzeug.datastructures [] []
shutil [] []
werkzeug.testapp [] []
dotenv [] []
flask_restx.fields [] []
winreg [] []
werkzeug.sansio.http [] []
pkgutil [] []
datetime [] []
werkzeug.urls ['fuzz_reqparse'] []
werkzeug.sansio [] []
logging [] []
werkzeug.datastructures.csp [] []
weakref [] []
tempfile [] []
watchdog [] []
flask_restx.schemas [] []
flask.views [] []
http [] []
codecs [] []
werkzeug.datastructures.cache_control [] []
flask.config [] []
calendar [] []
flask [] []
enum [] []
pathlib [] []
flask_restx [] []
string [] []
ujson [] []
aniso8601 [] []
multiprocessing [] []
flask.sessions [] []
collections [] []
werkzeug [] []
random [] []
hashlib [] []
contextvars [] []
flask_restx.namespace [] []
getpass [] []
functools [] []
selectors [] []
flask_restx.postman [] []
threading [] []
ssl [] []
werkzeug.sansio.request [] []
flask.globals [] []
flask_restx.marshalling [] []
flask.ctx ['fuzz_reqparse'] []
json [] []
time [] []
flask_restx.cors [] []
werkzeug.user_agent [] []
flask_restx.swagger [] []
flask_restx.reqparse ['fuzz_reqparse'] []
werkzeug.wrappers.request ['fuzz_reqparse'] []
werkzeug.formparser [] []
werkzeug.routing [] []
flask_restx.mask [] []
signal [] []
flask.app ['fuzz_reqparse'] []
re [] []
profile [] []
...fuzz_reqparse ['fuzz_reqparse'] []
werkzeug.datastructures.mixins [] []
secrets [] []
posixpath [] []
werkzeug.debug.tbtools [] []
decimal [] []
werkzeug.utils [] []
werkzeug.datastructures.accept [] []
flask_restx.resource [] []
flask_restx.utils [] []
flask_restx.errors ['fuzz_reqparse'] []
werkzeug.wsgi ['fuzz_reqparse'] []
flask.signals [] []
markupsafe [] []
flask_restx.apidoc [] []
flask_restx.model [] []
pydoc [] []
difflib [] []
dataclasses [] []
flask_restx.inputs [] []
rlcompleter [] []
werkzeug.routing.exceptions [] []
werkzeug.local [] []
werkzeug.sansio.multipart ['fuzz_reqparse'] []
werkzeug.http [] []
colorama [] []
flask.helpers [] []
math [] []
urllib [] []
pstats [] []
importlib [] []
types [] []
werkzeug._internal ['fuzz_reqparse'] []
[] []
werkzeug.datastructures.etag [] []
click [] []
flask.json.provider [] []
itsdangerous [] []
werkzeug.sansio.response [] []
flask.logging [] []
flask_restx.api [] []
socket [] []
readline [] []
werkzeug.middleware [] []
werkzeug.middleware.proxy_fix [] []
werkzeug.routing.rules [] []
asgiref [] []
werkzeug.serving [] []
flask.sansio.scaffold [] []
copy [] []
werkzeug.datastructures.file_storage [] []
flask.typing [] []
io [] []
termios [] []
flask.json.tag [] []
jsonschema [] []
werkzeug.datastructures.headers ['fuzz_reqparse'] []
werkzeug.test ['fuzz_reqparse'] []
werkzeug.wrappers.response [] []
werkzeug.security [] []
werkzeug.datastructures.auth [] []
operator [] []
jinja2 [] []
werkzeug.debug.repr [] []
inspect [] []
werkzeug.debug.console [] []
unicodedata [] []
atexit [] []
werkzeug.exceptions [] []
warnings [] []
subprocess [] []
importlib_metadata [] []
email [] []
sysconfig [] []
flask.wrappers [] []
werkzeug.middleware.profiler [] []
flask.sansio.app [] []
contextlib [] []
werkzeug.routing.matcher [] []
flask.sansio.blueprints [] []
flask.cli [] []
flask.json [] []
platform [] []
os [] []

Directories in report

Directory

Metadata section

This sections shows the raw data that is used to produce this report. This is mainly used for further processing and developer debugging.

Fuzzer Calltree file Program data file Coverage file
fuzz_reqparse fuzzerLogFile-fuzz_reqparse.data fuzzerLogFile-fuzz_reqparse.data.yaml all_cov.json