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

ImpactAn 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. PatchesThis has been fixed in pypdf==6.13.1. WorkaroundsIf users cannot upgrade yet, consider applying the changes from PR 3839...

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

ImpactAn 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. PatchesThis has been fixed in pypdf==6.13.0. WorkaroundsIf you cannot upgrade yet, consider applying the changes from PR 3830...

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

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires extracting the text in layout mode. PatchesThis has been fixed in pypdf==6.13.0. WorkaroundsIf you cannot upgrade yet, consider applying the changes from PR 3830...

PYSEC-2026-3009 pypdf: Possible infinite loop when retrieving fonts for layout-mode text extraction

Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires extracting the text in layout mode. Patches This has been fixed in pypdf==6.13.0. Workarounds If you cannot upgrade yet, consider applying the changes from PR 3830...

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-2026-3022 pypdf: Possible infinite loop when processing outlines/bookmarks in writer

Impact 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. Patches This has been fixed in pypdf==6.13.0. Workarounds If you cannot upgrade yet, consider applying the changes from PR 3830...

pypdf: Inefficient decoding of FlateDecode PNG predictor streams

ImpactAn 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. PatchesThis has been fixed in pypdf==6.12.2. WorkaroundsIf you cannot upgrade yet, consider applying the changes fr...

PYSEC-2026-3020 pypdf: Possible large memory usage for form XObjects during text extraction

Impact 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. Patches This has been fixed in pypdf==6.12.2. Workarounds If you cannot upgrade yet, consider applying...

pypdf: Manipulated XMP metadata streams can exhaust RAM

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing large XMP metadata, possibly with lots of unnecessary elements. PatchesThis has been fixed in pypdf==6.12.1. WorkaroundsIf you cannot upgrade yet, consider applying the changes...

PYSEC-2026-3016 pypdf: Possible large memory usage for large offsets for layout mode text

Impact An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires extracting text in layout mode with large character offsets. Patches This has been fixed in pypdf==6.12.0. Workarounds If developers are unable to immediately upgrade, they should...

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: Possible large memory usage for large offsets for layout mode text

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires extracting text in layout mode with large character offsets. PatchesThis has been fixed in pypdf==6.12.0. WorkaroundsIf developers are unable to immediately upgrade, they should consider...

pypdf: Manipulated FlateDecode image dimensions can exhaust RAM

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing an image using /FlateDecode with large size values. PatchesThis has been fixed in pypdf==6.10.2. WorkaroundsIf you cannot upgrade yet, consider applying the changes from P...

PYSEC-2026-3007 pypdf: Possible long runtimes for wrong size values in incremental mode

Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires loading a PDF with a large trailer /Size value in incremental mode. Patches This has been fixed in pypdf==6.10.2. Workarounds If you cannot upgrade yet, consider applying the changes from PR...

PYSEC-2026-3026 pypdf: Manipulated FlateDecode image dimensions can exhaust RAM

Impact An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing an image using /FlateDecode with large size values. Patches This has been fixed in pypdf==6.10.2. Workarounds If you cannot upgrade yet, consider applying the changes fro...

PYSEC-2026-3011 pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM

Impact An attacker who uses this vulnerability 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. Patches This has been fixed in pypdf==6.10.2. Workarounds If you cannot...

pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM

ImpactAn attacker who uses this vulnerability 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. PatchesThis has been fixed in pypdf==6.10.2. WorkaroundsIf you cannot...

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,...