What’s Vulnerable › Vulnerabilities

CVE-2026-84310: pypdf: Possible long runtimes/large memory usage when retrieving outlines

• 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: 2026-09-01 · updated 2026-10-05
• Weakness: CWE-405

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_doc_common.py _get_outline to consume long runtimes and large amounts of memory when retrieving document outlines with large numbers of entries or deeply nested reused paths because the traversal lacked global entry-count and nesting-depth limits. This issue is fixed in version 6.16.1.

Affected products

• py-pdf pypdf: before 6.16.1 — fixed in 6.16.1

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.16.1. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/d91ab705fd81ed1a9cec175c6958600dea1a4942
• https://github.com/py-pdf/pypdf/pull/3966
• https://github.com/py-pdf/pypdf/releases/tag/6.16.1
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-23w6-3w8w-8484

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