# CVE-2026-119204: pypdf excessive memory consumption in PDF page tree parsing

Source: https://junglewise.ai/threats/cve-2026-119204-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-29. Updated: 2026-10-29  
License: CC BY 4.0 with a link back

CVE-2026-119204 · Severity: high · CVSS 4 · Published 2026-10-29

pypdf is a Python library for reading and manipulating PDF files. A crafted PDF file can cause the library to consume excessive memory when parsing its page structure, potentially leading to application slowdown or denial of service. The vulnerability affects versions prior to 6.21.4.

Technologies: [Py-Pdf Pypdf](https://junglewise.ai/threats/technologies/py-pdf-pypdf), [pypdf (PyPI)](https://junglewise.ai/threats/technologies/pypdf). Vendors: [Py-Pdf](https://junglewise.ai/threats/vendors/py-pdf), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-119204 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-119204 being exploited in the wild.

**How severe is CVE-2026-119204?** High severity, with a CVSS score of 4, published 29 October 2026.

**Which products and versions are affected?** Py-Pdf Pypdf before 6.21.4; pypdf (PyPI) < 6.21.4, ECOSYSTEM:introduced=0,fixed=6.21.4.

**Is there a fix for CVE-2026-119204?** Yes. pypdf (PyPI): upgrade to 6.21.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-119204 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-119204?** Check whether you run Py-Pdf Pypdf or pypdf (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pypdf (PyPI): upgrade to 6.21.4 or later

  ```sh
  pip install "pypdf>=6.21.4"
  ```


## Technical details

pypdf's page-tree flattening function copies page dictionaries and inherited resource entries without enforcing a document-wide entry budget, allowing a crafted PDF with many shared resources to cause disproportionate memory allocations. An attacker can provide a malicious PDF file that triggers excessive memory consumption when processed by applications using pypdf. The issue is fixed by limiting the number of copied page attributes during flattening.

## Affected products

- py-pdf pypdf before 6.21.4

## Identifiers

- CVE-2026-119204
- GHSA-cggf-277g-3q54

## Timeline

- 2026-10-29: disclosed
- 2026-10-29: patched

## References

- [https://github.com/py-pdf/pypdf/commit/ea4ac663133f1b3de1d7a8f2e6fa239802fde79e](https://github.com/py-pdf/pypdf/commit/ea4ac663133f1b3de1d7a8f2e6fa239802fde79e)
- [https://github.com/py-pdf/pypdf/pull/4290](https://github.com/py-pdf/pypdf/pull/4290)

## Related threats

- [pypdf memory exhaustion in cross-reference stream parsing](https://junglewise.ai/threats/cve-2026-119209-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf denial of service via forged encrypted PDF page count](https://junglewise.ai/threats/cve-2026-119208-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf excessive memory consumption in strict mode PDF parsing](https://junglewise.ai/threats/cve-2026-119207-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf denial of service via crafted page labels](https://junglewise.ai/threats/cve-2026-119206-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf infinite loop in DictionaryObject cloning](https://junglewise.ai/threats/cve-2026-119205-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)