PYSEC-2026-3019 pypdf: manipulated stream length values can exhaust RAM

Impact 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. Patches This has been fixed in pypdf==6.8.0. Workarounds If you canno...

pypdf vulnerable to inefficient decoding of ASCIIHexDecode streams

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /ASCIIHexDecode filter. PatchesThis has been fixed in pypdf==6.7.5. WorkaroundsIf you cannot upgrade yet, consider applying the changes from PR 3666...

PYSEC-2026-3014 pypdf vulnerable to inefficient decoding of ASCIIHexDecode 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 /ASCIIHexDecode filter. Patches This has been fixed in pypdf==6.7.5. Workarounds If you cannot upgrade yet, consider applying the changes from PR 3666...

PYSEC-2026-3017 pypdf: Manipulated RunLengthDecode streams can exhaust RAM

Impact An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode filter. Patches This has been fixed in pypdf==6.7.4. Workarounds If you cannot upgrade yet, consider applying the changes from PR 36...

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...

pypdf: Manipulated RunLengthDecode streams can exhaust RAM

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode filter. PatchesThis has been fixed in pypdf==6.7.4. WorkaroundsIf you cannot upgrade yet, consider applying the changes from PR 3664...

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 a possible infinite loop when processing TreeObject

ImpactAn 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. PatchesThis has been fixed in pypdf==6.7.1. WorkaroundsIf you cannot upgrade yet, consider applying the changes fro...

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...

PYSEC-2026-3008 pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character

Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if parsecontentstream is executed. 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...

pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character

ImpactAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if parsecontentstream is executed. 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...

PT-2026-59638

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...

PT-2026-59642

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...

PT-2026-59649

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...

PT-2026-59628

Impact An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the XMP metadata. Patches This has been fixed in pypdf==6.10.0. Workarounds If you cannot upgrade yet, consider applying the changes from PR 3724...