CVE-2026-31826

Updated on 10 Mar 2026

Severity

6.8 Medium severity

Details

CVSS score
6.8
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Overview

About vulnerability

Impact

An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large /Length value, regardless of the actual data length inside the stream.

Patches

This has been fixed in pypdf==6.8.0.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3675.

As far as we are aware, this mostly affects reading from buffers of unknown size, as returned by open("file.pdf", mode="rb") for example. Passing a file path or a BytesIO buffer to pypdf instead does not seem to trigger the vulnerability.

Details

Affected product:
pypdf
Affected packages:
pypdf @ 5.9.0