---
id: CVE-2026-48156
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 6.12.0, an
  attacker who uses this vulnerability can craft a PDF which leads to long
  runtimes. This requires cross-reference streams with /W [0 0 0] values and
  large /Size …
severity: low
cvss: 3.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L'
cwe:
  - CWE-834
vendor: pypdf_project
product: pypdf
affected:
  - pypdf < 6.12.0
patched:
  - pypdf 6.12.0
published: '2026-05-28'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48156'
references:
  - url: 'https://github.com/py-pdf/pypdf/pull/3791'
    label: security-advisories@github.com
  - url: 'https://github.com/py-pdf/pypdf/releases/tag/6.12.0'
    label: security-advisories@github.com
  - url: 'https://github.com/py-pdf/pypdf/security/advisories/GHSA-248m-82v9-q6g6'
    label: security-advisories@github.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48156'
  - url: >-
      https://github.com/py-pdf/pypdf/commit/507d7c9aa6ea83389b954b9c3c0c528fe5d5da70
  - url: 'https://github.com/py-pdf/pypdf'
  - url: 'https://github.com/advisories/GHSA-248m-82v9-q6g6'
tags:
  - nvd
  - osv
  - pip
  - ghsa
epss: 0.00124
epssPercentile: 0.02113
aliases:
  - GHSA-248m-82v9-q6g6
  - PYSEC-2026-3004
ecosystem: pip
ingestedAt: '2026-07-07T15:41:59.222Z'
---

## Overview

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.

## Affected

- `pypdf < 6.12.0`

## Remediation

Upgrade past the affected range:

- `pypdf 6.12.0`

## Package advisory (CVE-2026-48156)

Affected packages:

- `pypdf < 6.12.0`

Patched in:

- `pypdf 6.12.0`

Source: https://osv.dev/vulnerability/GHSA-248m-82v9-q6g6