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CVE-2023-46250 — pypdf possible Infinite Loop when PdfWriter(clone_from) is used with a PDF

2026-10-06T03:12:44.891204+00:00

Affected: py-pdf pypdf

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions 3.7.0 through 3.16.4 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 incoming malicious PDF e.g. by merging it with another PDF or by adding annotations. The issue was fixed in version 3.17.0. As a workaround, apply the patch manually by modifying `pypdf/generic/_data_structures.py`.

GHSA-wjcc-cq79-p63f — Possible Infinite Loop when PdfWriter(clone_from) is used with a PDF

2026-10-06T03:12:44.891327+00:00

Affected: PyPI: pypdf

### 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 incoming malicious PDF e.g. by merging it with another PDF or by adding annotations.

### Patches The issue was fixed with #2264

### Workarounds If you cannot update your version of pypdf, you should modify `pypdf/generic/_data_structures.py` just like #2264 did.

PYSEC-2026-1834 — Possible Infinite Loop when PdfWriter(clone_from) is used with a PDF

2026-10-06T03:12:44.891384+00:00

Affected: PyPI: pypdf

That is, for example, the case when the pypdf-user manipulates an incoming malicious PDF e.g. by merging it with another PDF or by adding annotations.

### Patches The issue was fixed with #2264

### Workarounds If you cannot update your version of pypdf, you should modify `pypdf/generic/_data_structures.py` just like #2264 did.