CVE-2026-33123: pypdf has inefficient decoding of array-based streams

March 18, 2026 (updated March 20, 2026)

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries.

References

github.com/advisories/GHSA-qpxp-75px-xjcp
github.com/py-pdf/pypdf
github.com/py-pdf/pypdf/pull/3686
github.com/py-pdf/pypdf/releases/tag/6.9.1
github.com/py-pdf/pypdf/security/advisories/GHSA-qpxp-75px-xjcp
nvd.nist.gov/vuln/detail/CVE-2026-33123

Code Behaviors & Features

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