pypdf 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.

Metrics

Attack Vector Local

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable no

Technical Impact partial

Affected Vendors & Products

Vendors Products
Py-pdf
  • Pypdf
Pypdf Project
  • Pypdf

Configuration 1 [-]

cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:*

No data.

References
Link Providers
https://www.spirityenterprise.com/pentest spirity
https://www.spirityenterprise.com/managed-detection-response spirity
https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 cve-icon cve-icon cve-icon
https://github.com/py-pdf/pypdf/pull/3644 cve-icon cve-icon cve-icon
https://github.com/py-pdf/pypdf/releases/tag/6.7.1 cve-icon cve-icon cve-icon
https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-27026 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-27026 cve-icon
History

Thu, 26 Feb 2026 05:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 24 Feb 2026 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Pypdf Project
Pypdf Project pypdf
CPEs cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:*
Vendors & Products Pypdf Project
Pypdf Project pypdf
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Mon, 23 Feb 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Py-pdf
Py-pdf pypdf
Vendors & Products Py-pdf
Py-pdf pypdf

Sat, 21 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1050
References
Metrics threat_severity

None

 cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Fri, 20 Feb 2026 21:30:00 +0000

Type Values Removed Values Added
Description pypdf 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.
Title pypdf possibly has long runtimes for malformed FlateDecode streams
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-24T18:47:02.304Z

Reserved: 2026-02-17T03:08:23.491Z

Link: CVE-2026-27026

cve-icon Vulnrichment

Updated: 2026-02-24T18:46:53.788Z

cve-icon NVD

Status : Analyzed

Published: 2026-02-20T22:16:29.023

Modified: 2026-02-24T15:13:39.513

Link: CVE-2026-27026

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-02-20T21:12:33Z

Links: CVE-2026-27026 - Bugzilla