pypdf manipulated LZWDecode streams can exhaust RAM

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-66019
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-11-26 00:15:51 UTC
Updated2026-10-19 13:10:00 UTC
Descriptionpypdf 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.

Risk And Classification

Primary CVSS: v4.0 6.6 MEDIUM from [email protected]

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.6MEDIUMCVSS: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/C...
4.0CNADECLARED6.6MEDIUMCVSS: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

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Py-pdf Pypdf affected < 6.4.0 Not specified

References

ReferenceSourceLinkTags
github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7 [email protected] github.com
github.com/py-pdf/pypdf/releases/tag/6.4.0 [email protected] github.com
aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos af854a3a-2127-422b-91ae-364da2661108 aydinnyunus.github.io
github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2 [email protected] github.com
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