pypdf vulnerable to inefficient decoding of ASCIIHexDecode streams

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.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-03-02 22:03:45 UTC
Updated
2026-03-06 21:56:41 UTC
GitHub reviewed
2026-03-02 22:03:45 UTC
NVD published
2026-03-06

EPSS Score

Score Percentile
0.05% 15.21%

CVSS Scores

Base score Version Severity Vector
6.9 4.0
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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.

Identifiers

CWEs

CWE id Name
CWE-407 Inefficient Algorithmic Complexity

Credits

  • kule500 (reporter)
  • stefan6419846 (analyst)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip pypdf < 6.7.5 6.7.5

References

cvelogic Threat Intelligence