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Vulnerabilities

Vulnerability · CVE-2021-3426

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

Published May 20, 2021 · catalog updated Oct 14, 2026 · There's a flaw in

Check if you run it

No confirmed exploitation is on record for CVE-2021-3426. EPSS is 1.88%. Act only if a listed version of There's a flaw in is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (There's a flaw in).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.88%
Remediation
Not established
Affected products
cpe debian/debian linux · cpe fedoraproject/fedora · cpe netapp/cloud backup · cpe python/python · cpe redhat/software collections

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

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

How to fix CVE-2021-3426

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-3426. EPSS is 1.88%. Act only if a listed version of There's a flaw in is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 9.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-200: Exposure of Sensitive Information; CWE-22: Path Traversal. EPSS 1.88%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

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

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

Freshness

Last verified in this catalog Oct 16, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.