# CVE-2026-115580: pypdf ReDoS in cross-reference table parsing

Source: https://junglewise.ai/threats/cve-2026-115580-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-23. Updated: 2026-10-23  
License: CC BY 4.0 with a link back

CVE-2026-115580 · Severity: high · CVSS 4 · Published 2026-10-23

pypdf is a Python library for reading and writing PDF files. An attacker can craft a malicious PDF with a cross-reference table that claims to contain more entries than the file can actually hold, causing the library to perform excessive processing and consume significant CPU time when opening the file. This results in a denial-of-service condition that can freeze applications using the library.

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

## Quick answers

**Is CVE-2026-115580 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-115580 being exploited in the wild.

**How severe is CVE-2026-115580?** High severity, with a CVSS score of 4, published 23 October 2026.

**Which products and versions are affected?** Pypdf before 6.21.2; pypdf (PyPI) < 6.21.2, ECOSYSTEM:introduced=0,fixed=6.21.2.

**Is there a fix for CVE-2026-115580?** Yes. pypdf (PyPI): upgrade to 6.21.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-115580 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-115580?** Check whether you run 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 6.21.2 or later

  ```sh
  pip install "pypdf>=6.21.2"
  ```


## Technical details

The vulnerability is a regular expression denial of service (ReDoS) attack vector triggered when parsing standard cross-reference (xref) tables in PDF files. When a crafted PDF declares an entry count that exceeds the actual file size, the parsing logic attempts to process non-existent data, leading to algorithmic complexity and long runtimes. The fix limits the xref table size to the actual file size as a baseline constraint.

## Affected products

- pypdf pypdf before 6.21.2

## Identifiers

- CVE-2026-115580
- GHSA-gmh7-3g9r-mjh5

## Timeline

- 2026-10-23: disclosed
- 2026-10-21: patched

## References

- [https://github.com/py-pdf/pypdf/commit/a3061e34b169d34478d520f5f049c53cfb1482b2](https://github.com/py-pdf/pypdf/commit/a3061e34b169d34478d520f5f049c53cfb1482b2)
- [https://github.com/py-pdf/pypdf/pull/4239](https://github.com/py-pdf/pypdf/pull/4239)

## 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)