# CVE-2026-27888: PYSEC-2026-3027 - pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

Source: https://junglewise.ai/threats/cve-2026-27888-pypdf-manipulated-flatedecode-xfa-streams-can-exhaust-ram  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-26  
License: CC BY 4.0 with a link back

CVE-2026-27888 · Severity: high · CVSS 7.5 · Published 2026-02-26

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. This has been fixed in pypdf 6.7.3. As a workaround, apply the patch manually.

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-2026-27888 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27888 being exploited in the wild.

**How severe is CVE-2026-27888?** High severity, with a CVSS score of 7.5, published 26 February 2026.

**Which products and versions are affected?** pypdf (PyPI) ECOSYSTEM:introduced=0,fixed=6.7.3.

**Is there a fix for CVE-2026-27888?** Yes. pypdf (PyPI): upgrade to 6.7.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-27888?** 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 6.7.3 or later

  ```sh
  pip install "pypdf>=6.7.3"
  ```


## Affected products

- Py-Pdf Pypdf
- pypdf (PyPI) ECOSYSTEM:introduced=0,fixed=6.7.3

## Identifiers

- CVE-2026-27888
- GHSA-x7hp-r3qg-r3cj
- PYSEC-2026-3027

## 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)