pypdf Trailer Size Vulnerability Leading to Excessive Processing Time

A performance-related vulnerability exists in the pypdf library, specifically in versions prior to 6.10.2. When a PDF with a large trailer '/Size' value is loaded in incremental mode, it can cause significantly prolonged processing times. This issue has been addressed in version 6.10.2. For users unable to upgrade, the changes from the latest patch can be applied manually as a workaround.

Impact

Exploitation of this vulnerability can lead to unusually long processing times when handling specific PDF files, potentially causing performance issues in applications that rely on the pypdf library.

Reproduction

The vulnerability can be reproduced by creating a PDF file with a large '/Size' value in the trailer, which is then opened using the pypdf library in incremental mode. This can be done by using the PdfWriter class with the 'incremental' parameter set to True, and writing a PDF file that includes a large trailer size. Once the PDF is loaded with these characteristics, the performance impact can be observed.

Remediation

Users can upgrade to pypdf version 6.10.2 or apply the changes from the latest patch manually.