CVE-2026-27026
pypdf possibly has long runtimes for malformed FlateDecode streams
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.
INFO
Published Date :
Feb. 20, 2026, 10:16 p.m.
Last Modified :
Feb. 24, 2026, 3:13 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update pypdf to version 6.7.1 or later.
- Apply security patches for pypdf.
- Validate PDF decompression logic.
Public PoC/Exploit Available at Github
CVE-2026-27026 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27026.
| URL | Resource |
|---|---|
| https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 | Patch |
| https://github.com/py-pdf/pypdf/pull/3644 | Issue Tracking Patch |
| https://github.com/py-pdf/pypdf/releases/tag/6.7.1 | Product Release Notes |
| https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h | Patch Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27026 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27026
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
# مستودع asrar-mared هذا هو المستودع الرئيسي لمجموعة **المارد الرقمي**، نقطة التحكم المركزية التي تجمع كل المشاريع والميول التقنية تحت راية واحدة. يمثل الأساس الذي تُبنى عليه الفروع الأخرى، ويُدار منه كل شيء من تنظيم الكود إلى إدارة المجتمع. للاطلاع على المستودع: [asrar-mared](https://github.com/asrar-mared)
HTML CSS
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27026 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27026 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Feb. 24, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:* versions up to (excluding) 6.7.1 Added Reference Type GitHub, Inc.: https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/py-pdf/pypdf/pull/3644 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/py-pdf/pypdf/releases/tag/6.7.1 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h Types: Patch, Vendor Advisory -
New CVE Received by [email protected]
Feb. 20, 2026
Action Type Old Value New Value 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. Added CVSS V4.0 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 Added CWE CWE-770 Added Reference https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 Added Reference https://github.com/py-pdf/pypdf/pull/3644 Added Reference https://github.com/py-pdf/pypdf/releases/tag/6.7.1 Added Reference https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h