CVE-2026-22691
MEDIUMpypdf < 6.6.0 - Denial of Service via Malformed startxref Processing
Title source: llmDescription
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.
References (4)
Core 4
Core References
Vendor Advisory, Mitigation x_refsource_confirm
https://github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhv
Issue Tracking, Patch x_refsource_misc
https://github.com/py-pdf/pypdf/pull/3594
Patch x_refsource_misc
https://github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45
Release Notes x_refsource_misc
https://github.com/py-pdf/pypdf/releases/tag/6.6.0
Scores
CVSS v3
5.3
EPSS
0.0039
EPSS Percentile
30.6%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-1333
CWE-400
Status
published
Products (2)
pypdf_project/pypdf
< 6.6.0
pypi/pypdf
0 - 6.6.0PyPI
Published
Jan 10, 2026
Tracked Since
Feb 18, 2026