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CVE-2025-66019

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Date: November 25, 2025

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.

Severity Score

Related Resources (7)

https://github.com/py-pdf/pypdf/releases/tag/6.4.0
https://nvd.nist.gov/vuln/detail/CVE-2025-66019
https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7
https://github.com/py-pdf/pypdf
https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2
https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j
https://www.mend.io/vulnerability-database/CVE-2025-66019

Severity Score

Weakness Type (CWE)

Uncontrolled Resource Consumption

CWE-400

Improper Handling of Highly Compressed Data (Data Amplification)

CWE-409

Top Fix

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Upgrade Version

Upgrade to version pypdf - 6.4.0;pypdf - 6.4.0;pypdf - 6.4.0;https://github.com/py-pdf/pypdf.git - 6.4.0

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CVSS v3.1

Base Score:
Attack Vector (AV): NETWORK
Attack Complexity (AC): LOW
Privileges Required (PR): NONE
User Interaction (UI): NONE
Scope (S): UNCHANGED
Confidentiality (C): NONE
Integrity (I): NONE
Availability (A): HIGH

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