PYSEC-2026-1834
Possible Infinite Loop when PdfWriter(clone_from) is used with a PDF
Quick fix
PYSEC-2026-1834 — pypdf: upgrade to the fixed version with the command below.
pip install --upgrade 'pypdf>=3.17.0'Details
### 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.
Are you affected?
Enter the version of the package you're using.
Affected packages
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-wjcc-cq79-p63f[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2023-46250[ADVISORY]
- https://github.com/py-pdf/pypdf/pull/2264[WEB]
- https://github.com/py-pdf/pypdf/commit/9b23ac3c9619492570011d551d521690de9a3e2d[WEB]
- https://github.com/py-pdf/pypdf[PACKAGE]
- https://pypi.org/project/pypdf[PACKAGE]
- https://github.com/advisories/GHSA-wjcc-cq79-p63f[ADVISORY]