CVE-2021-3426

Severity: medium (CVSS 5.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-20 · updated 2026-10-14
Weakness: CWE-200

Description

There's a flaw in Python 3's pydoc. A local or adjacent attacker who discovers or is able to convince another local or adjacent user to start a pydoc server could access the server and use it to disclose sensitive information belonging to the other user that they would not normally be able to access. The highest risk of this flaw is to data confidentiality. This flaw affects Python versions before 3.8.9, Python versions before 3.9.3 and Python versions before 3.10.0a7.

Affected products

Debian Linux: 9.0
Fedoraproject Fedora: 32, 33, 34
NetApp Cloud Backup: all versions
NetApp ONTAP Select Deploy administration utility: all versions
NetApp SnapCenter: all versions
Oracle Communications Cloud Native Core Binding Support Function: 1.10.0
Oracle Corporation Oracle ZFS Storage Appliance Kit: 8.8
Python: before 2.7.18; from 3.6.0 before 3.6.13; from 3.7.0 before 3.7.10; from 3.8.0 before 3.8.8; from 3.9.0 before 3.9.3; 3.10.0-alpha1, 3.10.0-alpha2, 3.10.0-alpha3, 3.10.0-alpha4, 3.10.0-alpha5, 3.10.0-alpha6 — fixed in 2.7.18, 3.6.13, 3.7.10, 3.8.8, 3.9.3
Red Hat Enterprise Linux: 8.0
RedHat Software Collections: all versions

How to fix

Upgrade to a fixed version: Python 2.7.18, 3.6.13, 3.7.10, 3.8.8. Check the vendor advisory for mitigations.

References

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