# CVE-2026-82398

## Summary

- **CVE ID:** CVE-2026-82398
- **Severity:** MEDIUM
- **CVSS Score:** 6.9 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N)
- **CWE:** CWE-407
- **Published:** Aug 31, 2026
- **Last Modified:** Sep 1, 2026

## Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.

## Affected Products

- py-pdf — pypdf (< 6.15.0)

## References

- [CNA](https://github.com/py-pdf/pypdf/security/advisories/GHSA-fc8x-2rww-xw9m)
- [CNA](https://github.com/py-pdf/pypdf/pull/3947)
- [CNA](https://github.com/py-pdf/pypdf/commit/4959848e057e37c218dccad7465259210923faaa)
- [CNA](https://github.com/py-pdf/pypdf/releases/tag/6.15.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.30%
- **EPSS Percentile:** 22.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-12._