---
id: CVE-2026-82398
title: pypdf is a free and open-source pure-python PDF library
summary: >-
  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…
severity: medium
cwe:
  - CWE-407
  - CWE-1046
vendor: pypdf
product: pypdf
affected:
  - pypdf < 6.15.0
patched:
  - pypdf 6.15.0
published: '2026-08-31'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T16:49:20.627'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82398'
references:
  - url: >-
      https://github.com/py-pdf/pypdf/commit/4959848e057e37c218dccad7465259210923faaa
    label: security-advisories@github.com
  - url: 'https://github.com/py-pdf/pypdf/pull/3947'
    label: security-advisories@github.com
  - url: 'https://github.com/py-pdf/pypdf/releases/tag/6.15.0'
    label: security-advisories@github.com
  - url: 'https://github.com/py-pdf/pypdf/security/advisories/GHSA-fc8x-2rww-xw9m'
    label: security-advisories@github.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82398'
  - url: 'https://github.com/advisories/GHSA-fc8x-2rww-xw9m'
  - url: 'https://github.com/py-pdf/pypdf'
  - url: 'https://pypi.org/project/pypdf'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-82398.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-82398'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2526567'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-82398'
tags:
  - nvd
  - ghsa
  - pip
  - osv
  - csaf
  - vex
  - red-hat
epss: 0.00524
epssPercentile: 0.41997
aliases:
  - GHSA-fc8x-2rww-xw9m
  - PYSEC-2026-3912
ecosystem: pip
ingestedAt: '2026-09-02T14:45:30.013Z'
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: vendor
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-82398)

Affected packages:

- `pypdf < 6.15.0`

Patched in:

- `pypdf 6.15.0`

Source: https://github.com/advisories/GHSA-fc8x-2rww-xw9m

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Ansible Automation Orchestrator 2026, Exploit Intelligence, Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux AI (RHEL AI) 3, … · no fix planned: Exploit Intelligence, Red Hat Ansible Automation Platform 2, Red Hat Quay 3, Ansible Automation Orchestrator 2026, … · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-82398.json)