CVE-2026-28804

pypdf: Inefficient decoding of ASCIIHexDecode streams

State: Published
Severity: 6.9 Medium
Published: Mar 6, 2026
Updated: Mar 6, 2026
Reserved: Mar 3, 2026

Description

pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.5, 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. This issue has been patched in version 6.7.5.

Scores

CVSS	Score	Vector	Source
4.0	6.9 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-407 Inefficient Algorithmic Complexity

Affected Products

Product	Versions
pypdfpy-pdf	< 6.7.5Affected

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-9m86-7pmv-2852
https://github.com/py-pdf/pypdf/pull/3666
https://github.com/py-pdf/pypdf/commit/648c627d2657447dfb1773412af05a0a5103b98f
https://github.com/py-pdf/pypdf/releases/tag/6.7.5

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