What’s Vulnerable › Vulnerabilities

CVE-2026-41168: pypdf has possible long runtimes for wrong size values in cross-reference and object streams

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-22 · updated 2026-06-17
• Weakness: CWE-834

Description

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.1 can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values. This has been fixed in pypdf 6.10.1. As a workaround, one may apply the changes from the patch manually.

Affected products

• py-pdf pypdf: before 6.10.1 — fixed in 6.10.1

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.10.1. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/62338e9d36419cf193ccec7331784f45df1d70b3
• https://github.com/py-pdf/pypdf/pull/3733
• https://github.com/py-pdf/pypdf/releases/tag/6.10.1
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-jj6c-8h6c-hppx

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