Medium 5.1Published Mar 20, 2026

CVE-2026-33123pypdf has inefficient decoding of array-based streams

Updated under an hour ago (Oct 27, 2026, 4:30 PM ET)

Does this affect you?

It affects py-pdf pypdf and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for py-pdf pypdf

Exploited in the last 30 days

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: 5.1 MEDIUM (v4.0, CNA)CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Weakness (CWE): CWE-400, CWE-407
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Mar 20, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

py-pdf pypdf py_pdf:pypdf (from the name)	before 6.9.1	CNA record
pypdf_project pypdf pypdf_project:pypdf	before 6.9.1	NVD

References

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-qpxp-75px-xjcp	x-refsource-confirm, patch, vendor-advisory
https://github.com/py-pdf/pypdf/pull/3686	x-refsource-misc, issue-tracking, patch
https://github.com/py-pdf/pypdf/releases/tag/6.9.1	x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.