What is CVE-2021-43858?

CVE-2021-43858 is a high-severity vulnerability in Minio, classified under Improper Privilege Management. CVSS score: 8.8/10. Published 2021-12-27.

How severe is CVE-2021-43858?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2021-43858 known to be exploited?

12 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Auth bypass in Minio

CVE-2021-43858

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.

Vulnerability class: Privilege Escalation

Published 2021-12-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.355 (98.4th percentile), scored 2026-09-29.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 98.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.355 · newest: 0.355 · change: 0.000

Affected products

Minio — versions < RELEASE.2021-12-27T07-23-18Z

Weakness classification (CWE)

Public proof-of-concept exploits

References

github.com/minio/minio/security/advisories/GHSA-j6jc-jqqc-p6cx (Patch, Third Party Advisory)
github.com/minio/minio/pull/13976 (Patch, Third Party Advisory)
github.com/minio/minio/pull/7949 (Patch, Third Party Advisory)
github.com/minio/minio/commit/5a96cbbeaabd0a82b0fe881378e7c21c85091abf (Patch, Third Party Advisory)
github.com/minio/minio/releases/tag/RELEASE.2021-12-27T07-23-18Z (Third Party Advisory, Release Notes)

Frequently asked questions

What is CVE-2021-43858?: CVE-2021-43858 is a high-severity vulnerability in Minio, classified under Improper Privilege Management. CVSS score: 8.8/10. Published 2021-12-27.
How severe is CVE-2021-43858?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2021-43858 known to be exploited?: 12 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.