CVE-2025-66019

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.

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

CWE-409 CWE-409

References

Other References

https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2 https://github.com/py-pdf/pypdf/releases/tag/6.4.0 https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7 https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/

Frequently Asked Questions

What is CVE-2025-66019? +

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.

How do I check if I'm vulnerable to CVE-2025-66019? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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