CVE-2026-102997: DoS

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.

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Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

CWE-407 CWE-407

References

Other References

https://github.com/py-pdf/pypdf/commit/d9d38cf99b115deb562d3b68f36c33027bc04f79 https://github.com/py-pdf/pypdf/pull/4073 https://github.com/py-pdf/pypdf/releases/tag/6.18.1 https://github.com/py-pdf/pypdf/security/advisories/GHSA-jw7q-gvrg-4vj3

Frequently Asked Questions

What is CVE-2026-102997? +

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.

How do I check if I'm vulnerable to CVE-2026-102997? +

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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