pypdf possibly has long runtimes for malformed FlateDecode streams

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-27026
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-02-20 22:16:29 UTC
Updated2026-11-02 16:06:04 UTC
Descriptionpypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.

Risk And Classification

Primary CVSS: v4.0 6.9 MEDIUM from [email protected]

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/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: 0.001910000 probability, percentile 0.087510000 (date 2026-11-02)

Problem Types: CWE-770 | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.9MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED6.9MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/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
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

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 < 6.7.1 Not specified

References

ReferenceSourceLinkTags
github.com/py-pdf/pypdf/releases/tag/6.7.1 [email protected] github.com Product, Release Notes
github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 [email protected] github.com Patch
github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h [email protected] github.com Patch, Vendor Advisory
github.com/py-pdf/pypdf/pull/3644 [email protected] github.com Issue Tracking, Patch
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