Vulnerability in pyyaml (DEBIAN-CVE-2020-14343)

Summary

Vulnerability in pyyaml (DEBIAN-CVE-2020-14343). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 5.3.1-4 or later.

Original description

The description as published by the source.

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.

Source: OSV.dev (Open Source Vulnerabilities) OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as DEBIAN-CVE-2020-14343 has been found in pyyaml.
Successful exploitation can lead to full system takeover.
What to do: upgrade pyyaml to 5.3.1-4 or later.
If unsure, ask your IT team or search "pyyaml DEBIAN-CVE-2020-14343" on the vendor's site.

DEBIAN-CVE-2020-14343 (pyyaml)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 5.3.1-4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in pyyaml.

📍 Affected scope

Check the vendor advisory for the affected versions of pyyaml.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 5.3.1-4.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'pyyaml' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'pyyaml' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で pyyaml を grep し、稼働しているサービス・バージョンを把握する。
2
Apply patch patch
```
Upgrade pyyaml to 5.3.1-4
```
ステージング環境で 5.3.1-4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
3
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Debian:12 pyyaml

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.3.1-4"}]}]

Debian:13 pyyaml

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.3.1-4"}]}]

Debian:14 pyyaml

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.3.1-4"}]}]

References

advisory security-tracker.debian.org