CVE-2020-14343

CRITICALNVD 9.89.8
EchelonGraph scoreLOW confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 6%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

A vulnerability was discovered in the PyYAML library in versions before 5.4, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. This flaw allows an attacker to execute arbitrary code on the system by abusing the python/object/new constructor. This flaw is due to an incomplete fix for CVE-2020-1747.

CVSS v3
9.8
EG Score
9.8(low)
EPSS
92.4%
KEV
Not listed

Published

February 9, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Jul 6, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: redhat.
generic🔴 Active Exploitation

.load() and FullLoader still vulnerable to fairly trivial RCE · Issue #420 · yaml/pyyaml · GitHub

https://github.com/yaml/pyyaml/issues/420
generic

Resolve CVE for PyYAML - CVE-2020-14343 · Issue #2252 · SeldonIO/seldon-core · GitHub

https://github.com/SeldonIO/seldon-core/issues/2252
redhat Patch Available

1860466 – (CVE-2020-14343) CVE-2020-14343 PyYAML: incomplete fix for CVE-2020-1747

Affected: Red Hat Enterprise Linux 8

https://bugzilla.redhat.com/show_bug.cgi?id=1860466

Vendor Advisories for CVE-2020-14343(1)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3-yaml (5.3.1-2ubuntu0.1) @ groovy2026-05-23ubuntu
redhatpython-pyyaml-0:5.4.1-1.el7pc2021-11-16redhat
redhatpython38-devel:3.8-8040020210420090415.6dfe838a2021-06-29redhat

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.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
pyyaml3.01 ... 5.4b2 (32 versions)5.4—

Data Freshness Timeline

(refreshed 8× in last 7d / 45× 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.

  1. 2026-07-11 08:24 UTCEPSS rescore
  2. 2026-07-09 19:06 UTCEPSS rescore
  3. 2026-07-08 15:11 UTCEPSS rescore
  4. 2026-07-07 13:43 UTCEPSS rescore
  5. 2026-07-06 16:25 UTCEPSS rescore
  6. 2026-07-06 16:25 UTCEPSS rescore
  7. 2026-07-06 02:20 UTCEPSS rescore
  8. 2026-07-05 02:27 UTCEPSS rescore
  9. 2026-07-04 06:28 UTCEPSS rescore
  10. 2026-07-01 15:03 UTCEPSS rescore
  11. 2026-07-01 15:03 UTCEPSS rescore
  12. 2026-06-30 23:20 UTCEPSS rescore
  13. 2026-06-30 23:20 UTCEPSS rescore
  14. 2026-06-29 14:04 UTCEPSS rescore
  15. 2026-06-29 14:04 UTCEPSS rescore
  16. 2026-06-28 04:54 UTCEPSS rescore
  17. 2026-06-28 04:54 UTCEPSS rescore
  18. 2026-06-27 03:06 UTCEPSS rescore
  19. 2026-06-25 13:47 UTCEPSS rescore
  20. 2026-06-25 13:47 UTCEPSS rescore
  21. 2026-06-24 14:03 UTCEPSS rescore
  22. 2026-06-24 14:03 UTCEPSS rescore
  23. 2026-06-24 12:48 UTCOSV refresh
  24. 2026-06-23 21:31 UTCEPSS rescore
  25. 2026-06-23 21:31 UTCEPSS rescore
Show 54 more
  1. 2026-06-22 14:23 UTCEPSS rescore
  2. 2026-06-22 14:23 UTCEPSS rescore
  3. 2026-06-21 14:54 UTCEPSS rescore
  4. 2026-06-21 14:54 UTCEPSS rescore
  5. 2026-06-21 01:57 UTCEPSS rescore
  6. 2026-06-21 01:57 UTCEPSS rescore
  7. 2026-06-19 19:23 UTCEPSS rescore
  8. 2026-06-19 19:23 UTCEPSS rescore
  9. 2026-06-18 17:50 UTCEPSS rescore
  10. 2026-06-18 17:50 UTCEPSS rescore
  11. 2026-06-17 17:50 UTCEPSS rescore
  12. 2026-06-17 17:50 UTCEPSS rescore
  13. 2026-06-16 17:50 UTCEPSS rescore
  14. 2026-06-16 17:50 UTCEPSS rescore
  15. 2026-06-15 17:46 UTCEPSS rescore
  16. 2026-06-14 23:15 UTCEPSS rescore
  17. 2026-06-14 23:15 UTCEPSS rescore
  18. 2026-06-13 22:58 UTCEPSS rescore
  19. 2026-06-13 22:58 UTCEPSS rescore
  20. 2026-06-12 23:09 UTCEPSS rescore
  21. 2026-06-11 13:58 UTCEPSS rescore
  22. 2026-06-10 22:16 UTCEPSS rescore
  23. 2026-06-10 22:16 UTCEPSS rescore
  24. 2026-06-10 13:20 UTCEPSS rescore
  25. 2026-06-08 14:15 UTCEPSS rescore
  26. 2026-06-08 14:15 UTCEPSS rescore
  27. 2026-06-07 17:16 UTCOSV refresh
  28. 2026-06-07 15:23 UTCEPSS rescore
  29. 2026-06-07 15:23 UTCEPSS rescore
  30. 2026-06-06 13:45 UTCEPSS rescore
  31. 2026-06-06 13:45 UTCEPSS rescore
  32. 2026-06-06 13:45 UTCEPSS rescore
  33. 2026-06-05 22:45 UTCEPSS rescore
  34. 2026-06-05 22:45 UTCEPSS rescore
  35. 2026-06-04 13:10 UTCEPSS rescore
  36. 2026-06-04 13:10 UTCEPSS rescore
  37. 2026-06-02 20:11 UTCEPSS rescore
  38. 2026-06-02 20:11 UTCEPSS rescore
  39. 2026-06-01 13:50 UTCEPSS rescore
  40. 2026-05-31 22:29 UTCEPSS rescore
  41. 2026-05-31 22:29 UTCEPSS rescore
  42. 2026-05-31 00:15 UTCEPSS rescore
  43. 2026-05-31 00:14 UTCEPSS rescore
  44. 2026-05-29 13:42 UTCEPSS rescore
  45. 2026-05-29 13:42 UTCEPSS rescore
  46. 2026-05-28 13:43 UTCEPSS rescore
  47. 2026-05-28 13:43 UTCEPSS rescore
  48. 2026-05-27 13:39 UTCEPSS rescore
  49. 2026-05-26 13:42 UTCEPSS rescore
  50. 2026-05-26 13:42 UTCEPSS rescore
  51. 2026-05-26 07:17 UTCEPSS rescore
  52. 2026-05-26 07:17 UTCEPSS rescore
  53. 2026-05-23 07:57 UTCEG score recompute
  54. 2026-05-23 07:57 UTCVendor advisory

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCj4k0m/loader-CVE-2020-14343
    First seen Apr 19, 2022

    A web application vulnerable to CVE-2020-14343 insecure deserialization leading to command execution in PyYAML package.

    Open source ↗

Frequently asked(5)

What is CVE-2020-14343?
CVE-2020-14343 is a critical vulnerability published on February 9, 2021. A vulnerability was discovered in the PyYAML library in versions before 5.4, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be…
When was CVE-2020-14343 disclosed?
CVE-2020-14343 was first published in the National Vulnerability Database on February 9, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-14343 actively exploited?
CVE-2020-14343 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 92.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-14343?
CVE-2020-14343 has a CVSS v3 base score of 9.8 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2020-14343?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-14343, 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.

Dependency Blast Radius

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