CVE-2021-21287Public exploitNetwork attack vector

Authenticated internal-service access via unvalidated request host

Published Feb 1, 2021 · Updated Aug 3, 2024

SSRF in the Browser API in MinIO before RELEASE.2021-01-30T00-20-58Z allows remote authenticated users to reach internal services. The web.LoginSTS handler builds a POST target from the request Host header and sends the supplied token before validating it. A reachable, enabled Browser API is required; the server can expose cloud metadata or contact otherwise unreachable HTTP services.

CVSS severity7.7
High
EPSS probability24.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in the Browser API in MinIO before RELEASE.2021-01-30T00-20-58Z allows remote authenticated users to reach internal services. The web.LoginSTS handler builds a POST target from the request Host header and sends the supplied token before validating it. A reachable, enabled Browser API is required; the server can expose cloud metadata or contact otherwise unreachable HTTP services.

The record

CVE
CVE-2021-21287
Published
Feb 1, 2021
Updated
Aug 3, 2024
Vendor
MinIO
Product
MinIO
Classifications
CWE-918, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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.2021-01-30T00-20-58Z

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

MinIO · MinIOversion=< RELEASE.2021-01-30T00-20-58Z

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
7.7GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

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 exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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