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  5. GHSA-m449-cwjh-6pw7

GHSA-m449-cwjh-6pw7: pypdf's LZWDecode streams be manipulated to exhaust RAM

November 24, 2025

An attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter.

This is a follow up to GHSA-jfx9-29x2-rv3j to align the default limit with the one for zlib.

References

  • github.com/advisories/GHSA-m449-cwjh-6pw7
  • github.com/py-pdf/pypdf
  • github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2
  • github.com/py-pdf/pypdf/releases/tag/6.4.0
  • github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j
  • github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7

Code Behaviors & Features

Detect and mitigate GHSA-m449-cwjh-6pw7 with GitLab Dependency Scanning

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Affected versions

All versions before 6.4.0

Fixed versions

  • 6.4.0

Solution

Upgrade to version 6.4.0 or above.

Impact 7.5 HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Learn more about CVSS

Weakness

  • CWE-400: Uncontrolled Resource Consumption
  • CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)

Source file

pypi/pypdf/GHSA-m449-cwjh-6pw7.yml

Spotted a mistake? Edit the file on GitLab.

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