CVE-2026-49460: pypdf: Inefficient decoding of FlateDecode PNG predictor streams

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-22 · updated 2026-10-25
Weakness: CWE-407

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.2, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /FlateDecode filter with a PNG predictor. This vulnerability is fixed in 6.12.2.

Affected products

py-pdf pypdf: before 6.12.2 — fixed in 6.12.2

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.12.2. Check the vendor advisory for mitigations.

References

https://github.com/py-pdf/pypdf/pull/3806
https://github.com/py-pdf/pypdf/releases/tag/6.12.2
https://github.com/py-pdf/pypdf/security/advisories/GHSA-5hgr-hg42-57jg

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