# CVE-2021-43858: User privilege escalation in MinIO

> A malicious client can escalate privileges by crafting an HTTP API call to update user policies in MinIO object storage.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-j6jc-jqqc-p6cx, MINI-2mgh-r4pj-945h, MINI-g8g3-mpv9-6rfw

## What is CVE-2021-43858?

CVE-2021-43858 is a high-severity vulnerability in minio, published on 27 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-863 (Incorrect Authorization), CWE-269 (Improper Privilege Management)

## Which versions are affected by CVE-2021-43858?

It affects 1 product.


Products: Minio Minio.

## How do I fix CVE-2021-43858?

Upgrade to a fixed version.

## Is CVE-2021-43858 being exploited?

There is no known exploitation of CVE-2021-43858 in the wild and no public exploit code.

Public exploit code:

- https://github.com/0rx1/cve-2021-43858 (github_poc): https://github.com/0rx1/cve-2021-43858
- https://github.com/khuntor/CVE-2021-43858-MinIO (github_poc): https://github.com/khuntor/CVE-2021-43858-MinIO

## Other vulnerabilities in minio

- [CVE-2023-28434](https://insights.sbomify.com/CVE-2023-28434/): MinIO Security Feature Bypass (high 8.8, exploited in the wild)
- [CVE-2023-28432](https://insights.sbomify.com/CVE-2023-28432/): MinIO Information Disclosure (high 7.5, exploited in the wild)
- [CVE-2020-11012](https://insights.sbomify.com/CVE-2020-11012/): Authentication bypass MinIO Admin API (critical 9.3)
- [CVE-2026-33322](https://insights.sbomify.com/CVE-2026-33322/): MinIO: JWT Algorithm Confusion in OIDC Authentication (critical 9.2)
- [CVE-2026-33419](https://insights.sbomify.com/CVE-2026-33419/): MinIO: LDAP login brute-force via user enumeration and missing rate limit (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43858 and fix it if it is affected.

What it is: CVE-2021-43858 is a high-severity vulnerability in minio, published on 27 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43858 in the wild and no public exploit code.

Affected product: minio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-43858/ (Markdown: https://insights.sbomify.com/CVE-2021-43858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43858
- OSV: https://osv.dev/vulnerability/CVE-2021-43858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43858/
Summaries are generated and may contain mistakes; the official description above is the record.