# CVE-2026-119209: pypdf memory exhaustion in cross-reference stream parsing

Source: https://junglewise.ai/threats/cve-2026-119209-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-2026-119209 · Severity: high · CVSS 4 · Published 2026-10-29

pypdf is a Python library for reading and manipulating PDF files. A crafted PDF with specially malformed cross-reference streams can cause the library to consume excessive memory when opening the file, potentially leading to application crashes or denial of service. The issue affects versions before 6.21.3.

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-2026-119209 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-119209 being exploited in the wild.

**How severe is CVE-2026-119209?** High severity, with a CVSS score of 4, published 29 October 2026.

**Which products and versions are affected?** Py-Pdf Pypdf before 6.21.3; pypdf (PyPI) < 6.21.3, ECOSYSTEM:introduced=0,fixed=6.21.3.

**Is there a fix for CVE-2026-119209?** Yes. pypdf (PyPI): upgrade to 6.21.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-119209 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-119209?** 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 6.21.3 or later

  ```sh
  pip install "pypdf>=6.21.3"
  ```


## Technical details

The vulnerability exists in pypdf's handling of PDF cross-reference (xref) streams, where highly compressible streams declaring large entry counts, combined with /Prev chains that multiply parsed entries and negative /Index counts that bypass per-stream limits, can cause unbounded memory allocation. This is a local attack requiring the victim to open a malicious PDF file. The fix adds a document-wide budget for xref stream entries and rejects negative /Index counts.

## Affected products

- py-pdf pypdf before 6.21.3

## Identifiers

- CVE-2026-119209
- GHSA-x3rh-gjgm-fmqc

## Timeline

- 2026-10-29: disclosed
- 2026-10-27: patched

## References

- [https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4](https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4)
- [https://github.com/py-pdf/pypdf/pull/4269](https://github.com/py-pdf/pypdf/pull/4269)

## Related threats

- [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)
- [pypdf excessive memory consumption in PDF page tree parsing](https://junglewise.ai/threats/cve-2026-119204-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)