Description
pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, 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 issue has been patched in version 6.4.0.
Published: 2025-11-25
Score: 6.6 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-m449-cwjh-6pw7 pypdf's LZWDecode streams be manipulated to exhaust RAM
History

Tue, 20 Jan 2026 19:30:00 +0000

Type Values Removed Values Added
References

Wed, 03 Dec 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Moderate

Thu, 27 Nov 2025 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Pypdf Project
Pypdf Project pypdf
Vendors & Products Pypdf Project
Pypdf Project pypdf

Wed, 26 Nov 2025 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 25 Nov 2025 23:45:00 +0000

Type Values Removed Values Added
Description pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, 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 issue has been patched in version 6.4.0.
Title pypdf manipulated LZWDecode streams can exhaust RAM
Weaknesses CWE-400
CWE-409
References
Metrics cvssV4_0

{'score': 6.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U'}

Subscriptions

Pypdf Project Pypdf
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-01-20T18:33:02.928Z

Reserved: 2025-11-21T01:08:02.613Z

Link: CVE-2025-66019

cve-icon Vulnrichment

Updated: 2026-01-20T18:33:02.928Z

cve-icon NVD

Status : Deferred

Published: 2025-11-26T00:15:51.263

Modified: 2026-04-15T00:35:42.020

Link: CVE-2025-66019

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-11-25T23:38:12Z

Links: CVE-2025-66019 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-11-27T09:45:24Z

Weaknesses