What is CVE-2026-59937?

CVE-2026-59937 is a high-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-07-08.

How severe is CVE-2026-59937?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Py-Pdf Pypdf

CVE-2026-59937

pypdf is a free and open-source pure-python PDF library. Prior to 6.14.0, an attacker can craft a PDF with repeated malformed cross-reference streams that cause pypdf to spend long runtimes recovering broken cross-reference table entries. This issue is fixed in version 6.14.0.

Vulnerability class: DoS (Denial of Service)

Published 2026-07-08 · last modified 2026-07-09.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (48.1th percentile), scored 2026-10-09.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.006 · change: +0.003

Affected products

Py-Pdf Pypdf — versions < 6.14.0
Pypdf Project

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

github.com/py-pdf/pypdf/security/advisories/GHSA-55h5-xmcq-c37v (Patch, Vendor Advisory)
github.com/py-pdf/pypdf/pull/3887 (Patch, Issue Tracking)
github.com/py-pdf/pypdf/commit/b5fc5aa714f4b696fb9b1deaa35a9e4a4eb50dae (Patch)
github.com/py-pdf/pypdf/releases/tag/6.14.0 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-59937?: CVE-2026-59937 is a high-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-07-08.
How severe is CVE-2026-59937?: High severity. CVSS v3 base score is 7.5 out of 10.