CVE-2023-46250 pypdf possible Infinite Loop when PdfWriter(clone_from) is used with a PDF
An attacker can cause a denial of service via infinite loop in pypdf when processing crafted PDFs, affecting applications using the library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-46250?
CVE-2023-46250 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 31 Oct 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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`.
Weakness: CWE-835
Which versions are affected by CVE-2023-46250?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | From 3.7.0 | 3.17.0 |
pypdf PyPI | From 3.7.0 | 3.17.0 |
pypdf PyPI | From 3.7.0 | 3.17.0 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2023-46250?
Upgrade pypdf to 3.17.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-46250 being exploited?
There is no known exploitation of CVE-2023-46250 in the wild and no public exploit code.
Other vulnerabilities in Pypdf Project Pypdf
- CVE-2026-102993 pypdf: Possible large memory usage when retrieving Roman page labels
- CVE-2026-102994 pypdf: Possible long runtimes/large memory usage when parsing indirect objects
- CVE-2026-102995 pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)
- CVE-2026-102996 pypdf: Possible large memory usage when parsing font data
- CVE-2026-102997 pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)
Sources
Also known as GHSA-wjcc-cq79-p63f, PYSEC-2026-1834, UBUNTU-CVE-2023-46250.