CVE-2025-66019

high

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.

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7

https://github.com/py-pdf/pypdf/releases/tag/6.4.0

https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2

https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/

Details

Source: Mitre, NVD

Published: 2025-11-26

Updated: 2026-01-20

Risk Information

CVSS v2

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

Severity: High

CVSS v3

Base Score: 9.1

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Severity: Critical

CVSS v4

Base Score: 8.7

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

Severity: High

EPSS

EPSS: 0.00046