CVE-2026-33699: pypdf: Possible infinite loop during recovery attempts in DictionaryObject.read_from_stream

Severity: high (CVSS 7.5 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: 2026-03-27 · updated 2026-06-17
Weakness: CWE-835

Description

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.2 have a vulnerability in which an attacker can craft a PDF which leads to an infinite loop. This requires reading a file in non-strict mode. This has been fixed in pypdf 6.9.2. If users cannot upgrade yet, consider applying the changes from the patch manually.

Affected products

py-pdf pypdf: before 6.9.2 — fixed in 6.9.2

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.9.2. Check the vendor advisory for mitigations.

References

https://github.com/py-pdf/pypdf/pull/3693
https://github.com/py-pdf/pypdf/releases/tag/6.9.2
https://github.com/py-pdf/pypdf/security/advisories/GHSA-87mj-5ggw-8qc3

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