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.

Project Subscriptions

Vendors Products
Pypdf Project Subscribe
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-9mvc-8737-8j8h pypdf possibly has long runtimes for malformed FlateDecode streams
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

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'}


Projects

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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

No data.

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

cve-icon OpenCVE Enrichment

Updated: 2026-02-23T14:35:04Z

Weaknesses