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

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
Report generation date: 2025-07-12

Project overview: python-pypdf

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
23.0%
186 / 793
Cyclomatic complexity statically reachable by fuzzers
25.0%
721 / 2937
Runtime code coverage of functions
14.0%
111 / 793

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 412 1065 15 17 430 1396 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 1853 97.7%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 42 2.21%
All colors 1895 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
677 422 pypdf.generic._utils.create_string_object call site: 00422 pypdf._reader.PdfReader.read
473 1418 ...fuzz_encryption.TestInputOne call site: 01418 pypdf._writer.PdfWriter.generate_file_identifiers
255 3 ...fuzz_encryption.TestInputOne call site: 00003 pypdf._reader.PdfReader.__init__
186 1125 pypdf._writer.PdfWriter.__init__ call site: 01125 pypdf._writer.PdfWriter.clone_document_from_reader
145 271 pypdf.generic._base.IndirectObject.get_object call site: 00271 pypdf._utils.read_non_whitespace
56 1344 ...fuzz_encryption.TestInputOne call site: 01344 pypdf.generic._fit.Fit.__init__
12 1401 pypdf.generic._fit.Fit.__init__ call site: 01401 pypdf.generic._base.is_null_or_none
11 1113 pypdf._writer.PdfWriter.__init__._get_clone_from call site: 01113 .isinstance
8 259 pypdf._writer.PdfWriter.get_object call site: 00259 pypdf._reader.PdfReader.get_object
6 1315 pypdf._writer.PdfWriter.__init__ call site: 01315 pypdf.generic._base.TextStringObject.get_original_bytes
6 1322 pypdf.generic._base.encode_pdfdocencoding call site: 01322 pypdf.generic._base.TextStringObject.get_original_bytes
5 1103 pypdf._writer.PdfWriter._add_object call site: 01103 pypdf._writer.PdfWriter._add_object

Runtime coverage analysis

Covered functions
169
Functions that are reachable but not covered
367
Reachable functions
412
Percentage of reachable functions covered
10.92%
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 118
pypdf._reader 86
pypdf._utils 21
pypdf.generic._data_structures 83
pypdf.generic._base 49
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 hitcount 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'] 92 0 0 5 5 306 0 1065 260
pypdf._writer.PdfWriter.append pypdf._writer 6 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 91 0 3 4 5 316 0 1107 246
pypdf._writer.PdfWriter.update_page_form_field_values pypdf._writer 6 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 71 0 8 21 11 295 1 1038 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'] 4 0 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'] 91 0 2 13 8 302 0 1048 83
pypdf._page.PageObject._merge_page pypdf._page 6 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 89 0 12 9 7 277 5 958 77
pypdf._doc_common.PdfDocCommon.get_form_text_fields pypdf._doc_common 2 ['N/A', 'N/A'] 6 0 1 3 4 37 0 125 76
pypdf.generic._data_structures.ContentStream._parse_content_stream pypdf.generic._data_structures 2 ['N/A', 'N/A'] 88 0 5 4 5 187 1 665 64
pypdf._writer.PdfWriter.remove_text pypdf._writer 2 ['N/A', 'N/A'] 90 0 3 4 5 266 0 926 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 0 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
40.0%
321 / 793
Cyclomatic complexity statically reachable by fuzzers
46.0%
1354 / 2937

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', '...fuzz_encryption.TestInputOne', 'pypdf._writer.PdfWriter.__init__', 'pypdf.generic._base.IndirectObject.get_object', 'pypdf.generic._fit.Fit.__init__', 'pypdf._writer.PdfWriter.__init__._get_clone_from', 'pypdf._writer.PdfWriter.get_object']

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 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 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']
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._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.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._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.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% []
Crypto.Util.Padding.pad 36 4 11.11% ['fuzz_encryption']
pypdf._codecs._codecs.LzwCodec.decode 34 0 0.0% []
Crypto.Cipher.ARC4.ARC4Cipher 36 10 27.77% ['fuzz_encryption']
Crypto.Cipher.AES.new 59 29 49.15% ['fuzz_encryption']
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% []

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
[] []
pathlib [] []
pypdf._codecs.pdfdoc [] []
xml [] []
pypdf._codecs [] []
pypdf._codecs.zapfding [] []
io [] []
pypdf._encryption ['fuzz_encryption'] []
uuid [] []
atheris [] []
pypdf.generic._fit ['fuzz_encryption'] []
tempfile [] []
pypdf._codecs._codecs [] []
base64 [] []
pypdf._text_extraction._text_extractor [] []
pypdf.generic._files [] []
pypdf.generic._outline [] []
pypdf.annotations._markup_annotations [] []
crlf_space_check [] []
pypdf._xobj_image_helpers [] []
pypdf.generic._viewerpref [] []
pypdf._crypt_providers._fallback ['fuzz_encryption'] []
pypdf._codecs.adobe_glyphs [] []
pypdf._text_extraction._layout_mode [] []
collections [] []
...fuzz_encryption ['fuzz_encryption'] []
pypdf._text_extraction [] []
logging [] []
pypdf.types [] []
pypdf._protocols [] []
pypdf._version [] []
decimal [] []
dataclasses [] []
get_display_str [] []
pypdf.generic._utils ['fuzz_encryption'] []
struct [] []
json [] []
pypdf._codecs.symbol [] []
pypdf._merger [] []
pypdf._crypt_providers._pycryptodome ['fuzz_encryption'] []
pypdf._utils ['fuzz_encryption'] []
secrets [] []
pypdf._cmap [] []
itertools [] []
subprocess [] []
pypdf.pagerange [] []
mult [] []
pypdf.papersizes [] []
pypdf.generic._base ['fuzz_encryption'] []
pypdf._crypt_providers [] []
pypdf._page_labels [] []
pypdf._text_extraction._layout_mode._text_state_params [] []
pypdf.filters ['fuzz_encryption'] []
pypdf._page ['fuzz_encryption'] []
datetime [] []
pypdf._codecs.std [] []
pypdf.annotations [] []
zlib [] []
Crypto [] []
hashlib [] []
pypdf.generic._image_inline [] []
PIL [] []
pypdf.errors [] []
pypdf._reader ['fuzz_encryption'] []
shutil [] []
typing [] []
get_text_operands [] []
cryptography [] []
pypdf._doc_common ['fuzz_encryption'] []
pypdf.xmp [] []
pypdf [] []
pypdf._text_extraction._layout_mode._text_state_manager [] []
math [] []
warnings [] []
pypdf._text_extraction._layout_mode._fixed_width_page [] []
pypdf._writer ['fuzz_encryption'] []
pypdf.generic._data_structures ['fuzz_encryption'] []
os [] []
pypdf._text_extraction._layout_mode._font_widths [] []
pypdf._crypt_providers._base [] []
enum [] []
pypdf.annotations._base [] []
pypdf.constants [] []
pypdf._crypt_providers._cryptography ['fuzz_encryption'] []
pypdf.generic._rectangle [] []
re [] []
pypdf._text_extraction._layout_mode._font [] []
pypdf.generic ['fuzz_encryption'] []
binascii [] []
[] []
_codecs [] []
pypdf.annotations._non_markup_annotations [] []

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