What’s Vulnerable › Vulnerabilities

CVE-2026-103000: pypdf: Possible large memory usage when retrieving alphabetical page labels

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-30 · updated 2026-10-05
• Weakness: CWE-400

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF can provide unusually large alphabetical page-label values that cause pypdf/_page_labels.py to generate strings beyond a reasonable page-label length when an application retrieves document page labels, consuming excessive memory and potentially making the application unavailable. This issue is fixed in version 6.19.0.

Affected products

• py-pdf pypdf: before 6.19.0 — fixed in 6.19.0

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.19.0. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/0d8b5a8832cde1ba308b5c27567b879b7b7eed4a
• https://github.com/py-pdf/pypdf/pull/4096
• https://github.com/py-pdf/pypdf/releases/tag/6.19.0
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-w23x-9jrw-r45c

Get alerted when CVE-2026-103000 or the next vulnerability affects your stack