PYSEC-2026-3010 pypdf: Inefficient decoding of FlateDecode PNG predictor streams

Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /FlateDecode filter with a PNG predictor. Patches This has been fixed in pypdf==6.12.2. Workarounds If you cannot upgrade yet, consider applying the changes...

PYSEC-2026-3004 pypdf: Possible long runtimes for zero-only width values in cross-reference streamsuntimes for zero-only width values in cross-reference streams

Impact 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. Patches This has been fixed in pypdf==6.12.0. Workarounds If developers are unable to upgrade their apps immediately, the...

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

ImpactAn 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. PatchesThis has been fixed in pypdf==6.12.0. WorkaroundsIf developers are unable to upgrade their apps immediately, they...

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

ImpactAn attacker who uses this vulnerability 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. PatchesThis has been fixed in pypdf==6.10.1. WorkaroundsIf you cannot upgrade yet, consider...

PYSEC-2026-3021 pypdf has long runtimes for wrong size values in cross-reference and object streams

Impact An attacker who uses this vulnerability 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. Patches This has been fixed in pypdf==6.10.1. Workarounds If you cannot upgrade yet,...

PYSEC-2026-3023 pypdf has inefficient decoding of array-based streams

Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries. Patches This has been fixed in pypdf==6.9.1. Workarounds If you cannot upgrade yet, consider applying the...

pypdf has inefficient decoding of array-based streams

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries. PatchesThis has been fixed in pypdf==6.9.1. WorkaroundsIf you cannot upgrade yet, consider applying the changes...

pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

ImpactAn 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. PatchesThis has been fixed in pypdf==6.7.3. WorkaroundsIf projects...

PYSEC-2026-3027 pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

Impact 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. Patches This has been fixed in pypdf==6.7.3. Workarounds If...

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

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. PatchesThis has been fixed in pypdf==6.7.2. WorkaroundsIf users cannot upgrade yet, consider applying the changes from PR 3655...

PYSEC-2026-3005 pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. Patches This has been fixed in pypdf==6.7.2. Workarounds If users cannot upgrade yet, consider applying the changes from PR 3655...

pypdf has possible long runtimes/large memory usage for large /ToUnicode streams

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires parsing the /ToUnicode entry of a font with unusually large values, for example during text extraction. PatchesThis has been fixed in pypdf==6.7.1. WorkaroundsIf...

pypdf possibly has long runtimes for malformed FlateDecode streams

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. PatchesThis has been fixed in pypdf==6.7.1. WorkaroundsIf you cannot upgrade yet, consider applying the changes...

PYSEC-2026-3024 pypdf has possible long runtimes/large memory usage for large /ToUnicode streams

Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires parsing the /ToUnicode entry of a font with unusually large values, for example during text extraction. Patches This has been fixed in pypdf==6.7.1. Workarounds ...

PYSEC-2026-3015 pypdf possibly has long runtimes for malformed FlateDecode streams

Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. Patches This has been fixed in pypdf==6.7.1. Workarounds If you cannot upgrade yet, consider applying the chang...

PT-2026-59626

Impact 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. Patches This has been fixed in pypdf==6.12.0. Workarounds If developers are unable to upgrade their apps immediately, the...

PT-2026-59643

Impact An attacker who uses this vulnerability 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. Patches This has been fixed in pypdf==6.10.1. Workarounds If you cannot upgrade yet,...

PT-2026-59604

Summary PackInfo. read uses an On^2 cumulative sum pattern where numstreams is read directly from the archive header. A crafted .7z archive with a large numstreams value causes excessive CPU consumption during SevenZipFile. init — no extraction is needed. A 50 KB archive takes 7 seconds of CPU...

CVE-2026-59937

A flaw was found in pypdf, a pure-python PDF library. A remote attacker could exploit this vulnerability by crafting a malicious PDF file containing repeated malformed cross-reference streams. This could cause the pypdf library to spend excessive time recovering broken cross-reference table...

SUSE CVE-2026-59937

pypdf is a free and open-source pure-python PDF library. Prior to 6.14.0, an attacker can craft a PDF with repeated malformed cross-reference streams that cause pypdf to spend long runtimes recovering broken cross-reference table entries. This issue is fixed in version 6.14.0...