CVE-2021-43858Network attack vector

Privilege escalation via AddUser policy-field injection

Published Dec 27, 2021 · Updated Aug 4, 2024

Privilege escalation in MinIO before RELEASE.2021-12-27T07-23-18Z allows remote authenticated users to gain higher privileges through the AddUser API. The handler decodes a password-update body as UserInfo and applies its attacker-supplied policy field while updating the caller's secret key or status. Valid MinIO credentials and knowledge of the Admin API are required, and successful exploitation changes the user's effective authorization policy.

CVSS severity8.8
High
EPSS probability35.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in MinIO before RELEASE.2021-12-27T07-23-18Z allows remote authenticated users to gain higher privileges through the AddUser API. The handler decodes a password-update body as UserInfo and applies its attacker-supplied policy field while updating the caller's secret key or status. Valid MinIO credentials and knowledge of the Admin API are required, and successful exploitation changes the user's effective authorization policy.

The record

CVE
CVE-2021-43858
Published
Dec 27, 2021
Updated
Aug 4, 2024
Vendor
MinIO
Product
MinIO
Classifications
CWE-269, T1098
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< RELEASE.2021-12-27T07-23-18Z

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

MinIO · MinIOversion=< RELEASE.2021-12-27T07-23-18Z

Published CVSS scores

8.8GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-269Improper Privilege Management
T1098Account Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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