What is GHSA-9mvc-8737-8j8h?

GHSA-9mvc-8737-8j8h is a security advisory published by GitHub Security Advisories with Medium severity. pypdf possibly has long runtimes for malformed FlateDecode streams

Which CVE IDs does GHSA-9mvc-8737-8j8h cover?

GHSA-9mvc-8737-8j8h covers the following CVE IDs: CVE-2026-27026. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

Which products are affected by GHSA-9mvc-8737-8j8h?

GHSA-9mvc-8737-8j8h affects 1 product, including: pip/pypdf:\u003c 6.7.1.

GHSA-9mvc-8737-8j8hMedium

pypdf possibly has long runtimes for malformed FlateDecode streams

Vendor

GitHub Security Advisories

Published

February 18, 2026

Last Modified

February 23, 2026

🔗 CVE IDs covered (1)

CVE-2026-27026 →

📋 Description

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used.

Patches

This has been fixed in pypdf==6.7.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3644.

🎯 Affected products1

pip/pypdf:< 6.7.1

🔗 References (6)

https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h
https://github.com/py-pdf/pypdf/pull/3644
https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016
https://github.com/py-pdf/pypdf/releases/tag/6.7.1
https://nvd.nist.gov/vuln/detail/CVE-2026-27026
https://github.com/advisories/GHSA-9mvc-8737-8j8h