CVE-2026-59938: pypdf: Possible large memory usage for wrong image dimensions

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-08 · updated 2026-10-25
Weakness: CWE-789

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.14.0, an attacker can craft a PDF with declared image size values that are much too large compared to the actual data, causing large memory usage in pypdf image parsing. This issue is fixed in version 6.14.0.

Affected products

py-pdf pypdf: before 6.14.0 — fixed in 6.14.0

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.14.0. Check the vendor advisory for mitigations.

References

https://github.com/py-pdf/pypdf/commit/c64583be16b8e8763d8777075f8ecbf382014b7a
https://github.com/py-pdf/pypdf/pull/3888
https://github.com/py-pdf/pypdf/releases/tag/6.14.0
https://github.com/py-pdf/pypdf/security/advisories/GHSA-5qjq-93h5-hrgp

Get alerted when CVE-2026-59938 or the next vulnerability affects your stack