CVE-2021-3426

MEDIUMNVD 5.75.7—
EchelonGraph scoreMEDIUM confidence

Score 5.7 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 5.7Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.7
EG Score
5.7(medium)
EG Risk
—
EPSS
77.3%
KEV
Not listed

Published

May 20, 2021

Last Modified

December 18, 2025

References (29)

Vendor Advisories for CVE-2021-3426(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpython3-0:3.6.8-41.el82021-11-09redhat
redhatpython39-devel:3.9-8050020210811100211.d428a79b2021-11-09redhat
redhatpython38-devel:3.8-8050020210811101222.e3d35cca2021-11-09redhat
redhatrh-python38-python-urllib3-0:1.25.7-7.el72021-08-24redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 50× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-07-22 22:48 UTCEG score recompute
  2. 2026-07-22 14:06 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
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  8. 2026-07-18 19:59 UTCOSV refresh
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  11. 2026-07-01 03:18 UTCOSV refresh
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  44. 2026-06-13 05:13 UTCOSV refresh
  45. 2026-06-12 23:10 UTCEPSS rescore
  46. 2026-06-11 13:58 UTCEPSS rescore
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  73. 2026-05-26 16:22 UTCEG score recompute
  74. 2026-05-26 16:22 UTCVendor advisory
  75. 2026-05-26 16:22 UTCGHSA enrichment

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-3426?
CVE-2021-3426 is a medium vulnerability published on May 20, 2021. 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…
When was CVE-2021-3426 disclosed?
CVE-2021-3426 was first published in the National Vulnerability Database on May 20, 2021, with the most recent update on December 18, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-3426 actively exploited?
CVE-2021-3426 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3426?
CVE-2021-3426 has a CVSS v3 base score of 5.7 (NVD).
How do I remediate CVE-2021-3426?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3426, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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