CVE-2020-14343

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 6.0% (93rd percentile of EPSS-scored CVEs). 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
Elevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 6.0%CVSS: 9.8Exploit: Elevated riskExposed services: Not assessed

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
9.8CRITICALmedium confidence
EG Risk
65
EG Risk 65/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
6.0%
EPSS %ILE
93rd
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: elevated) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

February 9, 2021

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Oct 4, 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
redhatMentions a patch (unverified)

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(2)

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 / EcosystemFix (by version range) / 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

(19 across 19 ecosystems)
Alpine:v3.11(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.3.1-r1: fixed in 5.3.1-r1
—
Alpine:v3.12(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.3.1-r1: fixed in 5.3.1-r1
—
Alpine:v3.13(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.3.1-r2: fixed in 5.3.1-r2
—
Alpine:v3.14(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.15(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.16(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.17(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.18(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.19(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.20(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
py3-yaml—
  • every version up to 5.4-r0: fixed in 5.4-r0
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
pyyaml—
  • every version up to 5.3.1-4: fixed in 5.3.1-4
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
pyyaml—
  • every version up to 5.3.1-4: fixed in 5.3.1-4
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
pyyaml—
  • every version up to 5.3.1-4: fixed in 5.3.1-4
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
pyyaml—
  • every version up to 5.3.1-4: fixed in 5.3.1-4
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
pyyaml3.01 ... 5.4b2 (32 versions)
  • every version up to 5.4: fixed in 5.4
—

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

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 7× in last 7d / 28× 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 163 total refreshes for this CVE.

  1. 2026-10-09 20:03 UTCEPSS rescore
  2. 2026-10-09 19:55 UTCOSV refresh
  3. 2026-10-08 16:38 UTCEPSS rescore
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  18. 2026-09-20 03:20 UTCOSV refresh
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  1. 2026-09-12 14:56 UTCEPSS rescore
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  7. 2026-09-04 05:03 UTCEPSS rescore
  8. 2026-09-02 14:08 UTCEPSS rescore
  9. 2026-09-01 06:53 UTCOSV refresh
  10. 2026-09-01 03:32 UTCEPSS rescore
  11. 2026-08-30 19:14 UTCEPSS rescore
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  22. 2026-08-15 06:37 UTCOSV refresh
  23. 2026-08-15 01:26 UTCEPSS rescore
  24. 2026-08-13 21:57 UTCEPSS rescore
  25. 2026-08-12 13:47 UTCEPSS rescore
  26. 2026-08-08 16:33 UTCEPSS rescore
  27. 2026-08-07 16:23 UTCEPSS rescore
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  35. 2026-07-30 18:21 UTCOSV refresh
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  41. 2026-07-23 14:15 UTCEPSS rescore
  42. 2026-07-23 14:15 UTCEPSS rescore
  43. 2026-07-23 01:49 UTCEG score recompute
  44. 2026-07-22 22:34 UTCEG score recompute
  45. 2026-07-22 14:05 UTCEPSS rescore
  46. 2026-07-21 15:22 UTCEPSS rescore
  47. 2026-07-21 15:22 UTCEPSS rescore
  48. 2026-07-20 17:04 UTCEPSS rescore
  49. 2026-07-19 14:28 UTCEPSS rescore
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  58. 2026-07-13 03:08 UTCOSV refresh
  59. 2026-07-12 05:44 UTCEPSS rescore
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  63. 2026-07-07 13:43 UTCEPSS rescore
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  75. 2026-06-28 04:54 UTCEPSS rescore

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 ↗

Related CVEs(same product + same vendor + same CWE)

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 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 6.0% probability of exploitation in the next 30 days (93rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-14343?
CVE-2020-14343 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-14343?
A fix for CVE-2020-14343 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2020-14343 are linked in the Vendor Advisories panel on this page.

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