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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.1 · CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2023-46250: 0.25% estimated exploitation activity in the next 30 days; percentile 17.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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/datastructures.py just like #2264 did.

Published by the source

31 Oct 2023, 22:22 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:12 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wjcc-cq79-p63f

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-wjcc-cq79-p63f

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# Patch Next advisory brief: CVE-2023-46250

Advisory: Possible Infinite Loop when PdfWriter(clone_from) is used with a PDF
IDs: CVE-2023-46250, GHSA-wjcc-cq79-p63f
Record: https://patchnext.com/advisories/cve-2023-46250 (revision 2, source checked 26 Oct 2026, 13:12 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pypdf 3.17.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pypdf: affected >= 3.7.0, < 3.17.0; fixed in 3.17.0

## Suggested inspection (read-only)
- `python -m pip show pypdf`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pypdf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-wjcc-cq79-p63f (OSV record GHSA-wjcc-cq79-p63f lists affected ranges: PyPI pypdf >=3.7.0 <3.17.0 (fixed))
- Verified: https://github.com/advisories/GHSA-wjcc-cq79-p63f (GitHub-reviewed advisory GHSA-wjcc-cq79-p63f lists affected ranges: PyPI pypdf >=3.7.0 <3.17.0)

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