What is CVE-2026-84311?

CVE-2026-84311 is a low-severity vulnerability in Py-Pdf Pypdf, classified under Excessive Iteration. CVSS score: 3.3/10. Published 2026-09-01.

How severe is CVE-2026-84311?

Low severity. CVSS v3 base score is 3.3 out of 10.

Vulnerability in Py-Pdf Pypdf

CVE-2026-84311

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_page.py PageObject._extract_text and PageObject.extract_xform_text to traverse a directed acyclic graph of reused form XObjects in which each form invokes a child multiple times, creating exponentially many traversal paths and causing long runtimes and large memory consumption. This issue is fixed in version 6.16.1.

Published 2026-09-01 · last modified 2026-10-05.

CVSS v3 metric

CVSS v3 base score 3.3 (Low). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.001 (2.6th percentile), scored 2026-10-17.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 2.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: -0.000

Affected products

Py-Pdf Pypdf — versions < 6.16.1
Pypdf Project

Weakness classification (CWE)

CWE-834 — Excessive Iteration

References

github.com/py-pdf/pypdf/security/advisories/GHSA-763m-79hh-57f2 (Patch, Vendor Advisory)
github.com/py-pdf/pypdf/pull/3966 (Patch)
github.com/py-pdf/pypdf/commit/d91ab705fd81ed1a9cec175c6958600dea1a4942 (Patch)
github.com/py-pdf/pypdf/releases/tag/6.16.1 (Release Notes)

Frequently asked questions

What is CVE-2026-84311?: CVE-2026-84311 is a low-severity vulnerability in Py-Pdf Pypdf, classified under Excessive Iteration. CVSS score: 3.3/10. Published 2026-09-01.
How severe is CVE-2026-84311?: Low severity. CVSS v3 base score is 3.3 out of 10.