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CVE-2021-4189 medium CVSS 5.3

Vulnerability in Python (CVE-2021-4189)

Summary

Vulnerability in Python (CVE-2021-4189). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

A flaw was found in Python, specifically in the FTP (File Transfer Protocol) client library in PASV (passive) mode. The issue is how the FTP client trusts the host from the PASV response by default. This flaw allows an attacker to set up a malicious FTP server that can trick FTP clients into connecting back to a given IP address and port. This vulnerability could lead to FTP client scanning ports, which otherwise would not have been possible.

Source: NIST National Vulnerability Database NVD GitHub Advisory

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 CVE-2021-4189 has been found in Python.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Python CVE-2021-4189" on the vendor's site.

CVE-2021-4189 (Python) — CWE-252 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
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 (CWE-252) exists in Python.

📍 Affected scope

Check the vendor advisory for the affected versions of Python.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ 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 'Python' . 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. 1
    Identify exposure identify 
    grep -r 'Python' . | 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 Python を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    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

Bitnami libpython
[{"type":"SEMVER","events":[{"introduced":"3.6.0"},{"fixed":"3.6.14"},{"introduced":"3.7.0"},{"fixed":"3.7.11"},{"introduced":"3.8.0"},{"fixed":"3.8.9"},{"introduced":"3.9.0"},{"fixed":"3.9.3"},{"introduced":"3.10.0"},{"fixed":"3.10.1"}]}]
Bitnami python-min
[{"type":"SEMVER","events":[{"introduced":"3.6.0"},{"fixed":"3.6.14"},{"introduced":"3.7.0"},{"fixed":"3.7.11"},{"introduced":"3.8.0"},{"fixed":"3.8.9"},{"introduced":"3.9.0"},{"fixed":"3.9.3"},{"introduced":"3.10.0"},{"fixed":"3.10.1"}]}]
Bitnami python
[{"type":"SEMVER","events":[{"introduced":"3.6.0"},{"fixed":"3.6.14"},{"introduced":"3.7.0"},{"fixed":"3.7.11"},{"introduced":"3.8.0"},{"fixed":"3.8.9"},{"introduced":"3.9.0"},{"fixed":"3.9.3"},{"introduced":"3.10.0"},{"fixed":"3.10.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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