Report generation date: 2025-07-11

Project overview: bs4

High level conclusions

The runtime code coverage of bs4_fuzzer covers 8.771% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Reachability and coverage overview

Functions statically reachable by fuzzers

29 / 542

Cyclomatic complexity statically reachable by fuzzers

143 / 1923

Runtime code coverage of functions

297 / 542

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
bs4_fuzzer	/src/bs4_fuzzer.py	285	864	9	5	158	914	bs4_fuzzer.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	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: bs4_fuzzer

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 0 285 70.3%

gold [1:9] 0 0.0%

yellow [10:29] 0 0.0%

greenyellow [30:49] 0 0.0%

lawngreen 50+ 120 29.6%

All colors 405 100

Color	Runtime hitcount	Callsite count	Percentage
red	0	285	70.3%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	120	29.6%
All colors	405	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
80	314	bs4.element.SoupStrainer._matches	call site: 00314	bs4.element.SoupStrainer._matches
67	95	bs4.element.SoupStrainer._normalize_search_value	call site: 00095	bs4.BeautifulSoup.decode
22	34	bs4.BeautifulSoup.__init__	call site: 00034	bs4.BeautifulSoup._check_markup_is_url
13	220	bs4.element.PageElement.extract	call site: 00220	bs4.element.PageElement.insert
12	10	bs4.BeautifulSoup.__init__	call site: 00010	bs4.builder.TreeBuilderRegistry.lookup
10	204	bs4.element.SoupStrainer._matches	call site: 00204	bs4.element.PageElement.replace_with
9	190	bs4.element.SoupStrainer.search	call site: 00190	bs4.element.SoupStrainer.search
8	86	...bs4_fuzzer.TestOneInput	call site: 00086	bs4.element.PageElement._find_all
7	179	bs4.element.PageElement._find_all	call site: 00179	bs4.element.ResultSet.__init__
7	235	bs4.element.PageElement.insert	call site: 00235	bs4.element.SoupStrainer._normalize_search_value
5	57	bs4.BeautifulSoup._check_markup_is_url	call site: 00057	bs4.BeautifulSoup.reset
5	63	bs4.BeautifulSoup.reset	call site: 00063	bs4.element.PageElement.setup

Runtime coverage analysis

Covered functions

321

Functions that are reachable but not covered

260

Reachable functions

285

Percentage of reachable functions covered

8.77%

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
...bs4_fuzzer	8
bs4	38
bs4.builder	7
bs4.element	245

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	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity
`bs4.element.Tag.select`	bs4.element	5	['N/A', 'N/A', 'N/A', 'N/A', 'N/A']	21	1	3	4	155	1	598	577
`bs4.element.Tag.decode`	bs4.element	4	['N/A', 'N/A', 'N/A', 'N/A']	5	10	16	9	25	0	93	76
`bs4.dammit.EncodingDetector.encodings`	bs4.dammit	1	['N/A']	2	7	8	6	17	0	60	48
`bs4.dammit.UnicodeDammit.__init__`	bs4.dammit	8	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	3	2	6	5	17	1	59	41

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

Functions statically reachable by fuzzers

134 / 542

Cyclomatic complexity statically reachable by fuzzers

612 / 1923

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	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/bs4_fuzzer.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=['bs4.element.SoupStrainer._matches', 'bs4.element.SoupStrainer._normalize_search_value', 'bs4.BeautifulSoup.__init__', 'bs4.element.PageElement.extract', 'bs4.element.SoupStrainer.search', '...bs4_fuzzer.TestOneInput', 'bs4.element.PageElement._find_all', 'bs4.element.PageElement.insert']

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
bs4.element.PageElement.insert	60	23	38.33%	['bs4_fuzzer']
bs4.element.Tag.__init__	40	17	42.5%	['bs4_fuzzer']
bs4.element.SoupStrainer._matches	48	20	41.66%	['bs4_fuzzer']
soupsieve.css_parser.CSSParser.parse_pseudo_class	67	20	29.85%	[]
soupsieve.css_parser.CSSParser.parse_pseudo_nth	33	13	39.39%	[]
soupsieve.css_parser.CSSParser.parse_selectors	102	46	45.09%	[]
soupsieve.css_match._Match.match_nth	64	6	9.375%	[]
soupsieve.css_match._Match.match_indeterminate.get_parent_form	42	3	7.142%	[]
soupsieve.css_match._Match.match_lang	60	2	3.333%	[]
soupsieve.css_match._Match.match_dir	46	1	2.173%	[]
soupsieve.css_match._Match.match_range	35	0	0.0%	[]
soupsieve.css_match._Match.match_selectors	44	2	4.545%	[]
soupsieve.css_match.SoupSieve.__repr__	49	25	51.02%	[]
m.start	624	216	34.61%	[]
s.append	93	45	48.38%	[]
bs4.builder._html5lib.TreeBuilderForHtml5lib.testSerializer.serializeElement	36	1	2.777%	[]
bs4.builder._html5lib.Element.reparentChildren	33	2	6.060%	[]
bs4.builder._htmlparser.parse_starttag	41	0	0.0%	[]
bs4.dammit.chardet_dammit	328	152	46.34%	[]
html.parser.attrfind.match	991	38	3.834%	[]
x.lower	584	268	45.89%	[]

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
	[]	[]
soupsieve.css_types	[]	[]
bs4.formatter	[]	[]
warnings	[]	[]
soupsieve.util	[]	[]
lxml	[]	[]
bs4.builder._htmlparser	[]	[]
codecs	[]	[]
bs4.dammit	[]	[]
io	[]	[]
unittest	[]	[]
pstats	[]	[]
functools	[]	[]
atheris	[]	[]
cchardet	[]	[]
pickle	[]	[]
bs4.diagnose	[]	[]
copy	[]	[]
bs4.builder._html5lib	[]	[]
soupsieve.__meta__	[]	[]
soupsieve.css_parser	[]	[]
unicodedata	[]	[]
bs4.builder._lxml	[]	[]
html	[]	[]
html5lib	[]	[]
	[]	[]
time	[]	[]
...bs4_fuzzer	['bs4_fuzzer']	[]
cProfile	[]	[]
chardet	[]	[]
soupsieve.css_match	[]	[]
sys	[]	[]
bs4.testing	[]	[]
bs4.element	['bs4_fuzzer']	[]
random	[]	[]
os	[]	[]
datetime	[]	[]
soupsieve	[]	[]
re	[]	[]
bs4	['bs4_fuzzer']	[]
bs4.builder	['bs4_fuzzer']	[]
tempfile	[]	[]
collections	[]	[]
traceback	[]	[]
copyreg	[]	[]
logging	[]	[]

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

bs4_fuzzer fuzzerLogFile-bs4_fuzzer.data fuzzerLogFile-bs4_fuzzer.data.yaml all_cov.json

Table of contents

Project overview: bs4

High level conclusions

Reachability and coverage overview

Fuzzers overview

Project functions overview

Fuzzer details

Fuzzer: bs4_fuzzer

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/bs4_fuzzer.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