Medium severity · published Mar 20, 2026
CVE-2026-33123
pypdf has inefficient decoding of array-based streams
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 29% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pypdf · py-pdf
< 6.9.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33123
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33123
Issue Tracking
https://github.com/py-pdf/pypdf/pull/3686
Product
https://github.com/py-pdf/pypdf/releases/tag/6.9.1
Patch
https://github.com/py-pdf/pypdf/security/advisories/GHSA-qpxp-75px-xjcp
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