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Inefficient decoding of ASCIIHexDecode streams

Moderate
stefan6419846 published GHSA-9m86-7pmv-2852 Mar 2, 2026

Package

pip pypdf (pip)

Affected versions

< 6.7.5

Patched versions

>= 6.7.5

Description

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /ASCIIHexDecode filter.

Patches

This has been fixed in pypdf==6.7.5.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3666.

Severity

Moderate

CVE ID

CVE-2026-28804

Weaknesses

Inefficient Algorithmic Complexity

An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. Learn more on MITRE.

Credits