CVE-2026-71870: pypdf: Possible large memory usage for large /ToUnicode streams

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-07 · updated 2026-10-24
Weakness: CWE-400

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, a crafted PDF can cause large memory consumption when pypdf/_cmap.py function parse_bfrange parses unusually large source-code or destination-string tokens in a font /ToUnicode CMap during text extraction. This issue is fixed in 6.15.0.

Affected products

py-pdf pypdf: before 6.15.0 — fixed in 6.15.0

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.15.0. Check the vendor advisory for mitigations.

References

https://github.com/py-pdf/pypdf/commit/afba8080e19d29a3c256a742b340995e695b35aa
https://github.com/py-pdf/pypdf/pull/3944
https://github.com/py-pdf/pypdf/releases/tag/6.15.0
https://github.com/py-pdf/pypdf/security/advisories/GHSA-fp3f-mc75-235c

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