Report generation date: 2025-08-28

Project overview: python-pypdf

High level conclusions

The runtime code coverage of fuzz_encryption covers 26.36% 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

182 / 805

Cyclomatic complexity statically reachable by fuzzers

702 / 2977

Runtime code coverage of functions

193 / 805

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_encryption	/src/fuzz_encryption.py	402	1088	15	15	412	1359	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 1144 60.4%

gold [1:9] 0 0.0%

yellow [10:29] 0 0.0%

greenyellow [30:49] 0 0.0%

lawngreen 50+ 747 39.5%

All colors 1891 100

Color	Runtime hitcount	Callsite count	Percentage
red	0	1144	60.4%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	747	39.5%
All colors	1891	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
243	1280	pypdf._writer.PdfWriter.write_stream	call site: 01280	pypdf._writer.PdfWriter.write
132	1104	pypdf._writer.PdfWriter.__init__	call site: 01104	pypdf._writer.PdfWriter.clone_document_from_reader
89	835	pypdf._reader.PdfReader._read_xref	call site: 00835	pypdf._reader.PdfReader._read_pdf15_xref_stream
61	966	pypdf._encryption.Encryption.verify	call site: 00966	pypdf._encryption.AlgV4.verify_owner_password
58	460	pypdf._reader.PdfReader.cache_indirect_object	call site: 00460	pypdf._reader.PdfReader.read
56	593	pypdf.generic._data_structures.ArrayObject.read_from_stream	call site: 00593	pypdf.generic._base.BooleanObject.read_from_stream
52	714	pypdf._reader.PdfReader._read_standard_xref_table	call site: 00714	pypdf._reader.PdfReader._rebuild_xref_table
38	419	pypdf._crypt_providers._fallback.CryptRC4.encrypt	call site: 00419	pypdf._reader.PdfReader.read
29	388	pypdf._encryption.Encryption._make_crypt_filter	call site: 00388	pypdf._encryption.CryptFilter.decrypt_object
28	232	pypdf.generic._data_structures.DictionaryObject.read_from_stream	call site: 00232	pypdf._reader.PdfReader.read
24	786	pypdf._reader.PdfReader._read_standard_xref_table	call site: 00786	pypdf._reader.PdfReader.read
15	1680	pypdf._crypt_providers._pycryptodome.CryptAES.encrypt	call site: 01680	pypdf._crypt_providers._cryptography.CryptAES.encrypt

Runtime coverage analysis

Covered functions

252

Functions that are reachable but not covered

296

Reachable functions

402

Percentage of reachable functions covered

26.37%

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	9
pypdf._writer	121
pypdf._reader	86
pypdf._utils	19
pypdf.generic._data_structures	89
pypdf.generic._base	40
pypdf._encryption	87
pypdf._crypt_providers._cryptography	17
pypdf._crypt_providers._fallback	7
pypdf._crypt_providers._pycryptodome	7
pypdf.generic._utils	26
pypdf._doc_common	10
pypdf._page	9
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._writer.PdfWriter.append`	pypdf._writer	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	94	3	4	5	297	0	1048	253
`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']	96	2	13	8	290	0	1013	243
`pypdf._page.VirtualListImages.__getitem__`	pypdf._page	2	['N/A', 'N/A']	95	0	5	5	291	0	1021	206
`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	109
`pypdf._writer.PdfWriter.update_page_form_field_values`	pypdf._writer	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	95	8	21	11	284	1	1006	108
`pypdf._page.PageObject._merge_page`	pypdf._page	6	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	94	12	9	7	265	5	923	77
`pypdf._doc_common.PdfDocCommon.get_form_text_fields`	pypdf._doc_common	2	['N/A', 'N/A']	6	1	3	4	37	0	125	76
`pypdf.generic._data_structures.ContentStream._parse_content_stream`	pypdf.generic._data_structures	2	['N/A', 'N/A']	102	5	4	5	180	1	644	64
`pypdf._writer.PdfWriter.remove_text`	pypdf._writer	2	['N/A', 'N/A']	94	3	4	5	254	0	891	54
`pypdf.generic._base.IndirectObject.clone`	pypdf.generic._base	4	['N/A', 'N/A', 'N/A', 'N/A']	74	1	5	5	185	2	646	38

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

Functions statically reachable by fuzzers

327 / 805

Cyclomatic complexity statically reachable by fuzzers

1367 / 2977

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._writer.PdfWriter.write_stream', 'pypdf._writer.PdfWriter.__init__', 'pypdf._reader.PdfReader._read_xref', 'pypdf._encryption.Encryption.verify', 'pypdf._reader.PdfReader.cache_indirect_object', 'pypdf.generic._data_structures.ArrayObject.read_from_stream', 'pypdf._reader.PdfReader._read_standard_xref_table', 'pypdf._crypt_providers._fallback.CryptRC4.encrypt', 'pypdf._encryption.Encryption._make_crypt_filter', 'pypdf.generic._data_structures.DictionaryObject.read_from_stream']

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._add_page	33	0	0.0%	[]
pypdf._writer.PdfWriter._update_field_annotation	68	1	1.470%	['fuzz_encryption']
pypdf._writer.PdfWriter.update_page_form_field_values	56	0	0.0%	[]
pypdf._writer.PdfWriter._write_increment	34	0	0.0%	['fuzz_encryption']
pypdf._writer.PdfWriter.compress_identical_objects.replace_in_obj	39	0	0.0%	[]
pypdf._writer.PdfWriter.remove_objects_from_page.clean_forms	40	0	0.0%	[]
pypdf._writer.PdfWriter.merge._process_named_dests	53	0	0.0%	[]
pypdf._writer.PdfWriter._insert_filtered_annotations	36	0	0.0%	[]
pypdf._reader.PdfReader.get_object	75	22	29.33%	['fuzz_encryption']
pypdf._reader.PdfReader.read	41	19	46.34%	['fuzz_encryption']
pypdf._reader.PdfReader._rebuild_xref_table	39	0	0.0%	['fuzz_encryption']
Crypto.Cipher.ARC4.ARC4Cipher	36	10	27.77%	['fuzz_encryption']
Crypto.Util.Padding.pad.encode	36	8	22.22%	['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	30	29.70%	['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.Destination.__init__	32	0	0.0%	[]
pypdf._page.PageObject._merge_resources.compute_unique_key	33	0	0.0%	[]
pypdf._page.PageObject._merge_page	51	0	0.0%	[]
pypdf._page.PageObject._merge_page_writer	70	0	0.0%	[]
pypdf._page.PageObject._extract_text	74	0	0.0%	[]
pypdf._page._VirtualList.__delitem__	36	0	0.0%	[]
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.generic._image_inline.extract_inline_AHx	31	0	0.0%	[]
pypdf.generic._image_inline.extract_inline_default	32	0	0.0%	[]
pypdf.filters.FlateDecode.decode	34	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	73	0	0.0%	[]
pypdf._text_extraction.crlf_space_check	37	0	0.0%	[]
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.generic._utils.read_string_from_stream	43	0	0.0%	['fuzz_encryption']
pypdf._codecs._codecs.LzwCodec.decode	34	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.types	[]	[]
pypdf.constants	[]	[]
pypdf.generic._utils	['fuzz_encryption']	[]
pypdf.generic._viewerpref	[]	[]
pypdf._codecs	[]	[]
pypdf.xmp	[]	[]
collections	[]	[]
pypdf.generic	[]	[]
decimal	[]	[]
pypdf.generic._image_inline	[]	[]
pypdf._crypt_providers._fallback	['fuzz_encryption']	[]
pypdf._protocols	[]	[]
pypdf.generic._data_structures	['fuzz_encryption']	[]
pypdf._reader	['fuzz_encryption']	[]
pypdf.annotations	[]	[]
pypdf._page_labels	[]	[]
pypdf._codecs.pdfdoc	[]	[]
pypdf._crypt_providers	[]	[]
pypdf.annotations._non_markup_annotations	[]	[]
pypdf._cmap	[]	[]
itertools	[]	[]
pypdf._xobj_image_helpers	[]	[]
pypdf._text_extraction._layout_mode._font_widths	[]	[]
pypdf.generic._files	[]	[]
cryptography	[]	[]
PIL	[]	[]
atheris	[]	[]
pypdf._codecs.zapfding	[]	[]
pypdf.filters	['fuzz_encryption']	[]
datetime	[]	[]
pypdf._encryption	['fuzz_encryption']	[]
pypdf.generic._fit	[]	[]
pypdf.generic._outline	[]	[]
...fuzz_encryption	['fuzz_encryption']	[]
Crypto	[]	[]
pypdf.generic._rectangle	[]	[]
io	[]	[]
struct	[]	[]
pypdf._crypt_providers._base	[]	[]
pypdf._utils	['fuzz_encryption']	[]
pypdf._text_extraction._layout_mode._text_state_manager	[]	[]
pypdf.papersizes	[]	[]
secrets	[]	[]
pypdf.generic._link	[]	[]
typing	[]	[]
pypdf.annotations._base	[]	[]
pypdf._writer	['fuzz_encryption']	[]
enum	[]	[]
get_display_str	[]	[]
pypdf._codecs.symbol	[]	[]
pypdf._codecs._codecs	[]	[]
dataclasses	[]	[]
pathlib	[]	[]
pypdf._crypt_providers._pycryptodome	['fuzz_encryption']	[]
uuid	[]	[]
pypdf	[]	[]
pypdf._doc_common	['fuzz_encryption']	[]
subprocess	[]	[]
tempfile	[]	[]
pypdf._version	[]	[]
warnings	[]	[]
json	[]	[]
pypdf.errors	[]	[]
math	[]	[]
pypdf._codecs.adobe_glyphs	[]	[]
get_text_operands	[]	[]
pypdf._codecs.std	[]	[]
pypdf._crypt_providers._cryptography	['fuzz_encryption']	[]
xml	[]	[]
pypdf._text_extraction._layout_mode._text_state_params	[]	[]
shutil	[]	[]
binascii	[]	[]
pypdf._text_extraction._text_extractor	[]	[]
pypdf.pagerange	[]	[]
pypdf.annotations._markup_annotations	[]	[]
mult	[]	[]
	[]	[]
base64	[]	[]
crlf_space_check	[]	[]
hashlib	[]	[]
pypdf._text_extraction._layout_mode	[]	[]
pypdf._text_extraction._layout_mode._font	[]	[]
zlib	[]	[]
re	[]	[]
logging	[]	[]
pypdf._text_extraction	[]	[]
pypdf._text_extraction._layout_mode._fixed_width_page	[]	[]
os	[]	[]
pypdf._page	['fuzz_encryption']	[]
_codecs	[]	[]
pypdf.generic._base	['fuzz_encryption']	[]

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