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Possible long runtimes/large memory usage when retrieving outlines

Moderate
stefan6419846 published GHSA-23w6-3w8w-8484 Aug 14, 2026

Package

pip pypdf (pip)

Affected versions

< 6.16.1

Patched versions

>= 6.16.1

Description

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.

Severity

Moderate

CVE ID

No known CVE

Weaknesses

Asymmetric Resource Consumption (Amplification)

The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is asymmetric. Learn more on MITRE.

Excessive Iteration

The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed. Learn more on MITRE.

Credits