Report generation date: 2025-07-11

Project overview: python-pypdf

High level conclusions

The runtime code coverage of fuzz_encryption covers 12.21% 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

199 / 803

Cyclomatic complexity statically reachable by fuzzers

761 / 2966

Runtime code coverage of functions

191 / 803

Fuzzers overview

Fuzzer	Fuzzer filename	Functions Reached	Functions unreached	Fuzzer depth	Files reached	Basic blocks reached	Cyclomatic complexity	Details
fuzz_encryption	/src/fuzz_encryption.py	434	1060	15	17	434	1463	fuzz_encryption.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_encryption

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 2036 97.8%

gold [1:9] 0 0.0%

yellow [10:29] 0 0.0%

greenyellow [30:49] 0 0.0%

lawngreen 50+ 45 2.16%

All colors 2081 100

Color	Runtime hitcount	Callsite count	Percentage
red	0	2036	97.8%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	45	2.16%
All colors	2081	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
679	419	pypdf.generic._utils.create_string_object	call site: 00419	pypdf._reader.PdfReader.read
361	1716	pypdf._writer.PdfWriter._write_increment	call site: 01716	pypdf._writer.PdfWriter._compute_document_identifier
200	1124	pypdf._writer.PdfWriter.__init__	call site: 01124	pypdf._writer.PdfWriter.clone_document_from_reader
163	3	...fuzz_encryption.TestInputOne	call site: 00003	pypdf._reader.PdfReader.__init__
150	1530	pypdf._writer.PdfWriter._write_increment	call site: 01530	pypdf.generic._data_structures.EncodedStreamObject.set_data
139	268	pypdf.generic._base.IndirectObject.get_object	call site: 00268	pypdf._utils.read_non_whitespace
97	167	pypdf.generic._base.NameObject.read_from_stream	call site: 00167	pypdf._reader.PdfReader.read
71	1441	pypdf._writer.PdfWriter.write	call site: 01441	pypdf._writer.PdfWriter.write_stream
56	1357	...fuzz_encryption.TestInputOne	call site: 01357	pypdf.generic._fit.Fit.__init__
32	1683	pypdf._writer.PdfWriter._write_increment	call site: 01683	pypdf.generic._data_structures.StreamObject.write_to_stream
14	1342	...fuzz_encryption.TestInputOne	call site: 01342	pypdf.generic._utils.create_string_object
13	1328	pypdf._writer.PdfWriter.__init__	call site: 01328	pypdf.generic._base.TextStringObject.get_original_bytes

Runtime coverage analysis

Covered functions

248

Functions that are reachable but not covered

381

Reachable functions

434

Percentage of reachable functions covered

12.21%

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.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_encryption	11
pypdf._writer	141
pypdf._reader	86
pypdf._utils	21
pypdf.generic._data_structures	93
pypdf.generic._base	54
pypdf._encryption	89
pypdf._crypt_providers._cryptography	17
pypdf._crypt_providers._fallback	7
pypdf._crypt_providers._pycryptodome	7
pypdf.generic._utils	33
pypdf._doc_common	10
pypdf._page	9
pypdf.generic._fit	2
pypdf.generic	1
pypdf.filters	59

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
`pypdf._page.VirtualListImages.__getitem__`	pypdf._page	2	['N/A', 'N/A']	65	0	5	5	305	0	1062	260
`pypdf._writer.PdfWriter.append`	pypdf._writer	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	69	3	4	5	317	0	1111	246
`pypdf._writer.PdfWriter.update_page_form_field_values`	pypdf._writer	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	66	8	21	11	294	1	1035	226
`pypdf._text_extraction._layout_mode._fixed_width_page.text_show_operations`	pypdf._text_extraction._layout_mode._fixed_width_page	4	['N/A', 'N/A', 'N/A', 'N/A']	5	10	6	5	49	0	163	115
`pypdf._page.PageObject.extract_text`	pypdf._page	9	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	68	2	13	8	301	0	1045	83
`pypdf._page.PageObject._merge_page`	pypdf._page	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	65	12	9	7	276	5	955	77
`pypdf._doc_common.PdfDocCommon.get_form_text_fields`	pypdf._doc_common	2	['N/A', 'N/A']	9	1	3	4	37	0	125	76
`pypdf.generic._data_structures.ContentStream._parse_content_stream`	pypdf.generic._data_structures	2	['N/A', 'N/A']	57	5	4	5	186	1	662	64
`pypdf._writer.PdfWriter.remove_text`	pypdf._writer	2	['N/A', 'N/A']	65	3	4	5	265	0	923	54
`pypdf.generic._data_structures.DictionaryObject._clone`	pypdf.generic._data_structures	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	1	4	11	7	18	0	61	37

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

Functions statically reachable by fuzzers

336 / 803

Cyclomatic complexity statically reachable by fuzzers

1400 / 2966

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_encryption.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=['pypdf.generic._utils.create_string_object', 'pypdf._writer.PdfWriter._write_increment', 'pypdf._writer.PdfWriter.__init__', '...fuzz_encryption.TestInputOne', 'pypdf.generic._base.IndirectObject.get_object', 'pypdf.generic._base.NameObject.read_from_stream', 'pypdf._writer.PdfWriter.write']

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
pypdf._writer.PdfWriter.__init__._get_clone_from	37	17	45.94%	['fuzz_encryption']
pypdf._writer.PdfWriter._update_field_annotation	70	2	2.857%	['fuzz_encryption']
pypdf._writer.PdfWriter.update_page_form_field_values	58	3	5.172%	['fuzz_encryption']
pypdf._writer.PdfWriter.remove_objects_from_page.clean_forms	35	1	2.857%	['fuzz_encryption']
pypdf._writer.PdfWriter.append	35	0	0.0%	[]
pypdf._writer.PdfWriter.merge	44	1	2.272%	['fuzz_encryption']
pypdf._writer.PdfWriter.merge._process_named_dests	46	2	4.347%	['fuzz_encryption']
pypdf._writer.PdfWriter._add_articles_thread	43	1	2.325%	['fuzz_encryption']
pypdf._writer.PdfWriter._set_page_label	31	2	6.451%	['fuzz_encryption']
pypdf._reader.PdfReader.get_object	75	0	0.0%	['fuzz_encryption']
pypdf._reader.PdfReader.read	41	0	0.0%	['fuzz_encryption']
pypdf._reader.PdfReader._read_standard_xref_table	75	0	0.0%	['fuzz_encryption']
pypdf._reader.PdfReader._rebuild_xref_table	39	0	0.0%	['fuzz_encryption']
pypdf.generic._data_structures.DictionaryObject._clone	50	0	0.0%	[]
pypdf.generic._data_structures.DictionaryObject.read_from_stream.read_unsized_from_stream	101	0	0.0%	['fuzz_encryption']
pypdf.generic._data_structures.TreeObject.insert_child	38	0	0.0%	[]
pypdf.generic._data_structures.ContentStream._read_inline_image	51	0	0.0%	[]
pypdf.generic._data_structures.read_object	40	2	5.0%	['fuzz_encryption']
pypdf.generic._data_structures.Destination.__init__	32	0	0.0%	['fuzz_encryption']
Crypto.Util.Padding.pad.tell	36	4	11.11%	['fuzz_encryption']
pypdf.filters.FlateDecode.decode	36	0	0.0%	['fuzz_encryption']
pypdf.filters.FlateDecode._decode_png_prediction	46	0	0.0%	['fuzz_encryption']
pypdf.filters.decode_stream_data	38	0	0.0%	['fuzz_encryption']
pypdf.filters._xobj_to_image._apply_alpha	76	0	0.0%	[]
pypdf.generic._image_inline.extract_inline_AHx	31	0	0.0%	[]
pypdf.generic._image_inline.extract_inline_default	32	0	0.0%	[]
pypdf.generic._utils.read_string_from_stream	43	0	0.0%	['fuzz_encryption']
pypdf.generic._utils.create_string_object	45	2	4.444%	['fuzz_encryption']
pypdf._codecs._codecs.LzwCodec.decode	34	0	0.0%	[]
pypdf._page.PageObject._merge_resources.compute_unique_key	36	2	5.555%	['fuzz_encryption']
pypdf._page.PageObject.replace_contents	31	1	3.225%	['fuzz_encryption']
pypdf._page.PageObject._merge_page	52	1	1.923%	['fuzz_encryption']
pypdf._page.PageObject._merge_page_writer	72	1	1.388%	['fuzz_encryption']
pypdf._page.PageObject._extract_text	75	1	1.333%	['fuzz_encryption']
pypdf._page._VirtualList.__delitem__	35	2	5.714%	['fuzz_encryption']
Crypto.Cipher.ARC4.ARC4Cipher	36	10	27.77%	['fuzz_encryption']
Crypto.Cipher.AES.new	59	29	49.15%	['fuzz_encryption']
pypdf._doc_common.PdfDocCommon._get_named_destinations	46	0	0.0%	[]
pypdf._doc_common.PdfDocCommon.get_pages_showing_field._get_inherited	39	2	5.128%	['fuzz_encryption']
pypdf._doc_common.PdfDocCommon._build_outline_item	46	0	0.0%	[]
pypdf._doc_common.PdfDocCommon._flatten	36	0	0.0%	['fuzz_encryption']
pypdf._cmap._parse_encoding	40	0	0.0%	[]
pypdf._cmap.parse_bfrange	35	0	0.0%	[]
pypdf._cmap.build_font_width_map	60	0	0.0%	[]
pypdf._encryption.Encryption.write_entry	36	0	0.0%	['fuzz_encryption']
pypdf._encryption.Encryption.read	40	0	0.0%	['fuzz_encryption']
pypdf._text_extraction._layout_mode._fixed_width_page.recurs_to_target_op	84	0	0.0%	[]
pypdf._text_extraction._layout_mode._font.Font.__post_init__	34	0	0.0%	[]
pypdf._text_extraction.crlf_space_check	37	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
	[]	[]
pypdf._page_labels	[]	[]
pypdf._text_extraction._layout_mode._text_state_params	[]	[]
pypdf._codecs.std	[]	[]
PIL	[]	[]
pypdf._text_extraction	[]	[]
pypdf._writer	['fuzz_encryption']	[]
pypdf.filters	['fuzz_encryption']	[]
pypdf.errors	[]	[]
pypdf._crypt_providers._pycryptodome	['fuzz_encryption']	[]
struct	[]	[]
cryptography	[]	[]
pypdf._protocols	[]	[]
pypdf._merger	[]	[]
pypdf.generic._base	['fuzz_encryption']	[]
pypdf._page	['fuzz_encryption']	[]
pypdf.generic._utils	['fuzz_encryption']	[]
json	[]	[]
pathlib	[]	[]
pypdf.generic._rectangle	[]	[]
typing	[]	[]
pypdf.generic._outline	[]	[]
binascii	[]	[]
pypdf._codecs	[]	[]
pypdf._crypt_providers	[]	[]
enum	[]	[]
zlib	[]	[]
pypdf.xmp	[]	[]
pypdf._text_extraction._layout_mode	[]	[]
pypdf._codecs.adobe_glyphs	[]	[]
base64	[]	[]
pypdf.generic._viewerpref	[]	[]
pypdf._crypt_providers._fallback	['fuzz_encryption']	[]
pypdf._reader	['fuzz_encryption']	[]
itertools	[]	[]
pypdf._utils	['fuzz_encryption']	[]
pypdf._text_extraction._layout_mode._font	[]	[]
subprocess	[]	[]
pypdf.papersizes	[]	[]
pypdf._doc_common	['fuzz_encryption']	[]
dataclasses	[]	[]
collections	[]	[]
uuid	[]	[]
pypdf._text_extraction._layout_mode._text_state_manager	[]	[]
pypdf._encryption	['fuzz_encryption']	[]
pypdf._crypt_providers._cryptography	['fuzz_encryption']	[]
pypdf._xobj_image_helpers	[]	[]
...fuzz_encryption	['fuzz_encryption']	[]
re	[]	[]
decimal	[]	[]
os	[]	[]
hashlib	[]	[]
io	[]	[]
tempfile	[]	[]
get_text_operands	[]	[]
shutil	[]	[]
pypdf	[]	[]
pypdf._codecs.pdfdoc	[]	[]
pypdf.types	[]	[]
pypdf.generic._image_inline	[]	[]
pypdf._text_extraction._layout_mode._font_widths	[]	[]
math	[]	[]
pypdf.generic._files	[]	[]
pypdf.generic._data_structures	['fuzz_encryption']	[]
logging	[]	[]
get_display_str	[]	[]
pypdf._crypt_providers._base	[]	[]
pypdf.pagerange	[]	[]
pypdf.annotations._non_markup_annotations	[]	[]
crlf_space_check	[]	[]
pypdf._codecs.zapfding	[]	[]
mult	[]	[]
datetime	[]	[]
pypdf.annotations._markup_annotations	[]	[]
pypdf.constants	[]	[]
pypdf._codecs.symbol	[]	[]
pypdf._codecs._codecs	[]	[]
pypdf._cmap	[]	[]
atheris	[]	[]
pypdf.annotations._base	[]	[]
pypdf._text_extraction._layout_mode._fixed_width_page	[]	[]
pypdf.annotations	[]	[]
pypdf.generic._fit	['fuzz_encryption']	[]
	[]	[]
xml	[]	[]
pypdf._version	[]	[]
warnings	[]	[]
Crypto	[]	[]
secrets	[]	[]
pypdf.generic	['fuzz_encryption']	[]
pypdf._text_extraction._text_extractor	[]	[]
_codecs	[]	[]

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_encryption fuzzerLogFile-fuzz_encryption.data fuzzerLogFile-fuzz_encryption.data.yaml all_cov.json

Table of contents

Project overview: python-pypdf

High level conclusions

Reachability and coverage overview

Fuzzers overview

Project functions overview

Fuzzer details

Fuzzer: fuzz_encryption

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_encryption.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