CVE-2026-33699

pypdf: Possible infinite loop during recovery attempts in DictionaryObject.read_from_stream

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.2 have a vulnerability in which an attacker can craft a PDF which leads to an infinite loop. This requires reading a file in non-strict mode. This has been fixed in pypdf 6.9.2. If users cannot upgrade yet, consider applying the changes from the patch manually.

CVSS 4.0 · 4.6 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-27628

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

CVSS 4.0 · 1.2 Low EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-71852

pypdf: Possible long runtimes/large memory usage for large CID font width ranges

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, a crafted PDF can cause long runtimes and large memory consumption when pypdf/_font.py function Font._collect_cid_character_widths expands unusually large CID font /W width ranges or excessive width entries during text extraction. This issue is fixed in 6.15.0.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-54651

pypdf: Possible infinite loop when processing threads/articles in writer

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-27024

pypdf has a possible infinite loop when processing TreeObject

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires accessing the children of a TreeObject, for example as part of outlines. This vulnerability is fixed in 6.7.1.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2023-46250

pypdf possible Infinite Loop when PdfWriter(clone_from) is used with a PDF

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions 3.7.0 through 3.16.4 can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case when the pypdf-user manipulates an incoming malicious PDF e.g. by merging it with another PDF or by adding annotations. The issue was fixed in version 3.17.0. As a workaround, apply the patch manually by modifying `pypdf/generic/_data_structures.py`.

CVSS 3.1 · 5.1 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-102997

pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)

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 4.0 · 8.7 High EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-49461

pypdf: Possible large memory usage for form XObjects during text extraction

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.2, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires extracting the text of a page which contains a form XObject with self-references. This vulnerability is fixed in 6.12.2.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2025-62707

pypdf affected by possible infinite loop when reading DCT inline images without EOF marker

pypdf is a free and open-source pure-python PDF library. Prior to version 6.1.3, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires parsing the content stream of a page which has an inline image using the DCTDecode filter. This has been fixed in pypdf version 6.1.3.

CVSS 4.0 · 6.6 Medium EPSS < 1% KEV · Not listed

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Py-pdf Pypdf Project

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Pypdf Pypdf

CVE-2026-84310

pypdf: Possible long runtimes/large memory usage when retrieving outlines

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_doc_common.py _get_outline to consume long runtimes and large amounts of memory when retrieving document outlines with large numbers of entries or deeply nested reused paths because the traversal lacked global entry-count and nesting-depth limits. This issue is fixed in version 6.16.1.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-24688

pypdf has possible Infinite Loop when processing outlines/bookmarks

pypdf is a free and open-source pure-python PDF library. An attacker who uses an infinite loop vulnerability that is present in versions prior to 6.6.2 can craft a PDF which leads to an infinite loop. This requires accessing the outlines/bookmarks. This has been fixed in pypdf 6.6.2. If projects cannot upgrade yet, consider applying the changes from PR #3610 manually.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-84311

pypdf: Possible long runtimes/large memory usage when extracting XForm objects

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_page.py PageObject._extract_text and PageObject.extract_xform_text to traverse a directed acyclic graph of reused form XObjects in which each form invokes a child multiple times, creating exponentially many traversal paths and causing long runtimes and large memory consumption. This issue is fixed in version 6.16.1.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-84309

pypdf: Possible infinite loop for TreeObject.insert_child

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-41168

pypdf has possible long runtimes for wrong size values in cross-reference and object streams

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.1 can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values. This has been fixed in pypdf 6.10.1. As a workaround, one may apply the changes from the patch manually.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf Pypdf Project

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Pypdf Pypdf

CVE-2026-54531

pypdf: Possible infinite loop when processing outlines/bookmarks in writer

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with outlines into a writer. This vulnerability is fixed in 6.13.0.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-54530

pypdf: Possible infinite loop when retrieving fonts for layout-mode text extraction

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires extracting the text in layout mode. This vulnerability is fixed in 6.13.0.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-48156

pypdf: Possible long runtimes for zero-only width values in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-119203

pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-119205

pypdf: Possible infinite loop when cloning dictionaries

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop when cloning or duplicating a crafted cyclic DictionaryObject. Clone traversal checked generated destination references rather than the original source references, allowing some source cycles to evade the visited-object check. This issue is fixed in version 6.21.4.

CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-41313

pypdf: Possible long runtimes for wrong size values in incremental mode

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to long runtimes. This requires loading a PDF with a large trailer `/Size` value in incremental mode. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Py-pdf

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Pypdf