pypdf has possible long runtimes for malformed startxref

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-22691
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-10 05:16:08 UTC
Updated2026-11-02 16:06:04 UTC
Descriptionpypdf 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.

Risk And Classification

Primary CVSS: v4.0 2.7 LOW from [email protected]

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.004330000 probability, percentile 0.376360000 (date 2026-11-02)

Problem Types: CWE-400 | CWE-1333 | CWE-1333 CWE-1333: Inefficient Regular Expression Complexity | CWE-400 CWE-400: Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.7LOWCVSS: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/C...
4.0CNADECLARED2.7LOWCVSS: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
3.1[email protected]Primary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Py-pdf Pypdf All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Py-pdf Pypdf affected < 6.6.0 Not specified

References

ReferenceSourceLinkTags
github.com/py-pdf/pypdf/pull/3594 [email protected] github.com Issue Tracking, Patch
github.com/py-pdf/pypdf/releases/tag/6.6.0 [email protected] github.com Release Notes
github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45 [email protected] github.com Patch
github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhv [email protected] github.com Mitigation, Vendor Advisory
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