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.
Advisories
Source ID Title
Debian DLA Debian DLA DLA-2619-1 python3.5 security update
Debian DLA Debian DLA DLA-3477-1 python3.7 security update
Debian DLA Debian DLA DLA-3980-1 python3.9 security update
EUVD EUVD EUVD-2021-26753 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.
Ubuntu USN Ubuntu USN USN-5342-1 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-5342-3 Python vulnerability
Ubuntu USN Ubuntu USN USN-6891-1 Python vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

References
History

Mon, 03 Nov 2025 22:30:00 +0000

Type Values Removed Values Added
References

Mon, 14 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00109}

epss

{'score': 0.00098}


Fri, 11 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00095}

epss

{'score': 0.00109}


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2025-11-03T21:44:51.975Z

Reserved: 2021-03-09T00:00:00.000Z

Link: CVE-2021-3426

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-05-20T13:15:07.753

Modified: 2025-11-03T22:15:50.480

Link: CVE-2021-3426

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-03-10T00:00:00Z

Links: CVE-2021-3426 - Bugzilla

cve-icon OpenCVE Enrichment

No data.