CVE-2020-1747

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 1.8%, top 17% of all CVEs by exploit prediction. 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: epss, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 5%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

A vulnerability was discovered in the PyYAML library in versions before 5.3.1, 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. An attacker could use this flaw to execute arbitrary code on the system by abusing the python/object/new constructor.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
91.6%
KEV
Not listed

Published

March 24, 2020

Last Modified

November 21, 2024

Advisory Details (7)

Auto-updated May 30, 2026
Patch available. Sources: redhat, github_pr.
generic

[SECURITY] Fedora 31 Update: PyYAML-5.3.1-1.fc31 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZBJA3SGNJKCAYPSHOHWY3KBCWNM5NYK2/
generic

[SECURITY] Fedora 30 Update: PyYAML-5.3.1-1.fc30 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WORRFHPQVAFKKXXWLSSW6XKUYLWM6CSH/
generic

[SECURITY] Fedora 33 Update: PyYAML-5.4.1-1.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MMQXSZXNJT6ERABJZAAICI3DQSQLCP3D/
generic

[SECURITY] Fedora 32 Update: PyYAML-5.3.1-1.fc32 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K5HEPD7LEVDPCITY5IMDYWXUMX37VFMY/
generic

[SECURITY] Fedora 32 Update: PyYAML-5.4.1-1.fc32 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7PPAS6C4SZRDQLR7C22A5U3QOLXY33JX/
github_pr Patch Available

Prevents arbitrary code execution during python/object/new constructor

Patch available: yaml/pyyaml 6.0.2rc1 (PR #386 merged 2020-03-17)

https://github.com/yaml/pyyaml/pull/386
redhat Patch Available

1807367 – (CVE-2020-1747) CVE-2020-1747 PyYAML: arbitrary command execution through python/object/new when FullLoader is used

Affected: Red Hat Enterprise Linux 8

https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1747

Vendor Advisories for CVE-2020-1747(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpython38:3.8-8030020200818121840.4190259b2020-11-04redhat

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
pyyaml5.1 ... 5.3 (7 versions)5.3.1—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

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

Frequently asked(5)

What is CVE-2020-1747?
CVE-2020-1747 is a critical vulnerability published on March 24, 2020. A vulnerability was discovered in the PyYAML library in versions before 5.3.1, 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-2020-1747 disclosed?
CVE-2020-1747 was first published in the National Vulnerability Database on March 24, 2020, 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-2020-1747 actively exploited?
CVE-2020-1747 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 91.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-1747?
CVE-2020-1747 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-1747?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-1747, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-1747

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