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Description

pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.

PUBLISHED Reserved 2026-01-08 | Published 2026-01-10 | Updated 2026-01-12 | Assigner GitHub_M




LOW: 2.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U

Problem types

CWE-1333: Inefficient Regular Expression Complexity

CWE-400: Uncontrolled Resource Consumption

Product status

< 6.6.0
affected

References

github.com/.../pypdf/security/advisories/GHSA-4f6g-68pf-7vhv

github.com/py-pdf/pypdf/pull/3594

github.com/...ommit/294165726b646bb7799be1cc787f593f2fdbcf45

github.com/py-pdf/pypdf/releases/tag/6.6.0

cve.org (CVE-2026-22691)

nvd.nist.gov (CVE-2026-22691)

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