CVE-2026-27888

pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. This has been fixed in pypdf 6.7.3. As a workaround, apply the patch manually.

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

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Py-pdf

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Pypdf

CVE-2026-71870

pypdf: Possible large memory usage for large /ToUnicode streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, a crafted PDF can cause large memory consumption when pypdf/_cmap.py function parse_bfrange parses unusually large source-code or destination-string tokens in a font /ToUnicode CMap 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-2026-27628

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-2026-41314

pypdf: Manipulated FlateDecode image dimensions can exhaust RAM

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 the RAM being exhausted. This requires accessing an image using `/FlateDecode` with large size values. 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

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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-2026-41313

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

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Py-pdf

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Pypdf

CVE-2026-41312

pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM

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 the RAM being exhausted. This requires accessing a stream compressed using `/FlateDecode` with a `/Predictor` unequal 1 and large predictor parameters. 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

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Py-pdf

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Pypdf

CVE-2026-31826

pypdf: manipulated stream length values can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.8.0, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large /Length value, regardless of the actual data length inside the stream. This vulnerability is fixed in 6.8.0.

CVSS 4.0 · 6.8 Medium EPSS < 1% KEV · Not listed

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Py-pdf

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Pypdf

CVE-2026-102993

pypdf: Possible large memory usage when retrieving Roman page labels

pypdf is a free and open-source pure-python PDF library. Prior to 6.17.0, a crafted PDF can provide unusually large Roman page-label values that cause pypdf/_page_labels.py to generate excessively large numeral strings when an application retrieves document page labels, consuming large amounts of memory and potentially making the application unavailable. This issue is fixed in version 6.17.0.

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

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Py-pdf

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Pypdf

CVE-2023-36464

Infinite Loop when a comment isn't followed by a character in pypdf

pypdf is an open source, pure-python PDF library. In affected versions an attacker may craft a PDF which leads to an infinite loop if `__parse_content_stream` is executed. That is, for example, the case if the user extracted text from such a PDF. This issue was introduced in pull request #969 and resolved in pull request #1828. Users are advised to upgrade. Users unable to upgrade may modify the line `while peek not in (b"\r", b"\n")` in `pypdf/generic/_data_structures.py` to `while peek not in (b"\r", b"\n", b"")`.

CVSS 3.1 · 6.2 Medium EPSS < 1% KEV · Not listed

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Py-pdf Pypdf2 Project

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Pypdf Pypdf2

CVE-2023-36807

Infinite Loop when reading malformed objects in pypdf

pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability 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 if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.

CVSS 3.1 · 6.2 Medium EPSS < 1% KEV · Not listed

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Py-pdf Pypdf Project

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Pypdf 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-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-2025-62708

pypdf manipulated LZWDecode streams can exhaust RAM

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 large memory usage. This requires parsing the content stream of a page using the LZWDecode 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-2026-102994

pypdf: Possible long runtimes/large memory usage when parsing indirect objects

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.0, a crafted PDF containing indirect-object identifiers or generation-number tokens that continue for a long time without whitespace can cause pypdf/_reader.py and pypdf/generic/_base.py to scan excessive input through read_until_whitespace, resulting in long runtimes and application unavailability. This issue is fixed in version 6.18.0.

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

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Py-pdf

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Pypdf

CVE-2026-102995

pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)

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

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Py-pdf

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Pypdf

CVE-2026-102996

pypdf: Possible large memory usage when parsing font data

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 4.0 · 8.7 High 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-2026-102998

pypdf: Possible long runtimes when generating appearance streams

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

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Py-pdf

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Pypdf

CVE-2026-102999

pypdf: Possible long runtimes with large amount of embedded files

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

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Py-pdf

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Pypdf