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Findings

CVE-2021-3426

There's a flaw in Python 3's pydoc.

Published May 20, 2021 · updated Oct 14, 2026 · python python

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.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 20, 2021 · NIST NVD

    Detected

    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

  2. Oct 14, 2026 · NIST NVD

    Updated

    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

Affected

  • cpe debian/debian linux9.0
  • cpe fedoraproject/fedora32
  • cpe netapp/cloud backupversion unspecified
  • cpe python/pythonversion unspecified
  • cpe python/python3.10.0
  • cpe redhat/software collectionsversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2021-3426

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-3426

    30-day exploitation probability 1.9%

    first.org
  • NIST NVDVulnerability recordCVE-2021-3426

    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 normal

    nvd.nist.gov

References