pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, calling PdfWriter.find_outline_item on a crafted PDF with a cyclic outline hierarchy can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.
CVSS Score
6.0
EPSS Score
0.003
Published
2026-10-21
pypdf is a free and open-source pure-python PDF library. Prior to 6.20.1, removing an object from a crafted cyclic PDF tree, such as an outline item, can enter an infinite loop and block the current process. This issue is fixed in version 6.20.1.
CVSS Score
6.0
EPSS Score
0.004
Published
2026-10-21
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.0, an attacker can craft a PDF that causes large memory usage or long runtimes when an application retrieves the document's form fields. This issue is fixed in version 6.21.0.
CVSS Score
6.0
EPSS Score
0.003
Published
2026-10-21
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.0, an attacker can craft a PDF containing arrays or dictionaries with many elements, causing parsing to consume large amounts of memory. This issue is fixed in version 6.21.0.
CVSS Score
6.0
EPSS Score
0.003
Published
2026-10-21
pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-09-30
pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF with form field values can cause pypdf/generic/_appearance_stream.py appearance-stream generation to repeat invariant selection-data work inside a loop when an application updates fields with flattening enabled, resulting in excessive runtimes and application unavailability. This issue is fixed in version 6.19.0.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-09-30
pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF containing many embedded files can cause the dictionary-based attachments API in pypdf/_doc_common.py to reparse the full attachment list for each content lookup, producing repeated work and long runtimes when an application accesses the embedded-file mapping. This issue is fixed in version 6.19.0.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-09-30
pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF can provide unusually large alphabetical page-label values that cause pypdf/_page_labels.py to generate strings beyond a reasonable page-label length when an application retrieves document page labels, consuming excessive memory and potentially making the application unavailable. This issue is fixed in version 6.19.0.
CVSS Score
8.7
EPSS Score
0.004
Published
2026-09-30
pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF can place unusually large source-code or destination-string tokens in a font /ToUnicode mapping, causing pypdf/_cmap.py parse_bfchar to decode and retain oversized values during operations such as text extraction and consume excessive memory. This is a second follow-up to earlier /ToUnicode resource-consumption fixes and is limited to the remaining token-length path. This issue is fixed in version 6.18.1.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-09-30
pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF can provide a TrueType or Type1 simple font with an unusually large /Widths array, causing pypdf/_font.py Font._collect_tt_t1_character_widths to process entries beyond the 256 character codes meaningful for a simple font and consume excessive memory during operations such as text extraction. This issue is fixed in version 6.18.1.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-09-30