Vulnerability in MinIO (CVE-2021-43858)

Summary

Vulnerability in MinIO (CVE-2021-43858). Successful exploitation can lead to full system takeover. Exploitable via Deny.

Original description

The description as published by the source.

MinIO is a Kubernetes native application for cloud storage. Prior to version RELEASE.2021-12-27T07-23-18Z, a malicious client can hand-craft an HTTP API call that allows for updating policy for a user and gaining higher privileges. The patch in version RELEASE.2021-12-27T07-23-18Z changes the accepted request body type and removes the ability to apply policy changes through this API. There is a workaround for this vulnerability: Changing passwords can be disabled by adding an explicit Deny rule to disable the API for users.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory 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 CVE-2021-43858 has been found in MinIO.
Attackers can target a specific entry point like Deny over the network to misuse the product.
Successful exploitation can lead to full system takeover.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "MinIO CVE-2021-43858" on the vendor's site.

CVE-2021-43858 (MinIO)
Attack vector: remote (network-reachable) / no user interaction
Attack surface: Deny
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 MinIO. Attackers reach the vulnerable code path via Deny.

📍 Affected scope

Check the vendor advisory for the affected versions of MinIO. Attack surface: Deny.

🔥 Severity

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

🔧 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 'MinIO' . 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 'MinIO' . | 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 MinIO を grep し、稼働しているサービス・バージョンを把握する。
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。

References

advisory github.com
patch github.com
patch github.com
patch github.com
patch github.com