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%, top 7% 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
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(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: Track*

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%
Action: Watch closely — could escalate to Attend.
EPSS
92.5%
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—

Weakness Classification(1)

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

Additional Vendor Advisories

(3)

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 13× in last 7d / 42× 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. 2026-07-23 01:49 UTCEG score recompute
  2. 2026-07-22 22:34 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
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  70. 2026-05-23 07:57 UTCEG score recompute
  71. 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 ↗

Related CVEs(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 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 92.5% 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).
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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