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...

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-2026-49730

Name of the Vulnerable Software and Affected Versions pypdf versions prior to 6.12.2 Description A flaw in the pure-python PDF library allows an attacker to craft a PDF that causes excessive memory consumption. This occurs when extracting text from a page containing a form XObject a reusable PDF...

PT-2026-49729

Name of the Vulnerable Software and Affected Versions pypdf versions prior to 6.12.2 Description An attacker can craft a PDF file that results in long runtimes. This occurs when accessing a stream that utilizes the /FlateDecode filter with a PNG predictor. Recommendations Update to version 6.12.2...

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

Impact 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 when the pypdf-user manipulates an incomi...