GHSA-23w6-3w8w-8484: Pip/pypdf vulnerability

Published Sep 1, 2026
·
Updated

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires accessing the outlines of a document with either lots of entries or nested outlines with long re-used nesting paths.

Patches

This has been fixed in pypdf==6.16.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3966.

Affected Software

1 affected componentFixes available
pip/pypdf<6.16.1
6.16.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade pip/pypdf to a version that resolves this vulnerability.

    Fixed in 6.16.1
  2. Upgrade

    Upgrade pypdf to a version that resolves this vulnerability.

    Fixed in 6.16.1
  3. Compensating control

    If you cannot upgrade yet, apply the changes from PR [#3966] to mitigate the long runtimes and large memory consumption when processing crafted PDFs that access document outlines with lots of entries or nested outlines with long re-used nesting paths.

Event History

Sep 1, 2026
Advisory Published
via GitHub·09:28 PM
Data Sourced
via GitHub·09:28 PM
DescriptionWeaknessAffected Software

Frequently Asked Questions

1

What conditions are required for exploitation?

An attacker must be able to supply a crafted PDF, and the application must access that document's outlines. The malicious PDF uses either many outline entries or deeply nested outlines with long reused nesting paths.

2

Which deployments are most exposed?

Deployments that process untrusted PDFs and access document outlines are exposed to the described resource-consumption behavior. The provided information does not establish whether merely opening or otherwise processing a PDF without accessing outlines is affected.

3

What should be done if an upgrade cannot be applied immediately?

Apply the changes from pypdf PR #3966 as a workaround. The issue is fixed in pypdf 6.16.1.

Contact

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