CVE-2025-31489Public exploitNetwork attack vector

Unauthorized object writes via ignored upload signatures

Published Apr 3, 2025 · Updated Apr 3, 2025

Signature bypass in MinIO before RELEASE.2025-04-03T14-56-28Z allows remote attackers to write arbitrary objects via unsigned-trailer uploads. PutObjectHandler and PutObjectPartHandler passed unsigned-trailer streams to newUnsignedV4ChunkedReader without requiring validation of the Authorization signature. Exploitation requires a valid access key with WRITE permission and the target bucket name, but not the corresponding secret key.

CVSS severity8.7
High
EPSS probability2.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature bypass in MinIO before RELEASE.2025-04-03T14-56-28Z allows remote attackers to write arbitrary objects via unsigned-trailer uploads. PutObjectHandler and PutObjectPartHandler passed unsigned-trailer streams to newUnsignedV4ChunkedReader without requiring validation of the Authorization signature. Exploitation requires a valid access key with WRITE permission and the target bucket name, but not the corresponding secret key.

The record

CVE
CVE-2025-31489
Published
Apr 3, 2025
Updated
Apr 3, 2025
Vendor
MinIO
Product
MinIO
Classifications
CWE-347, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2025Record 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.2025-04-03T14-56-28Z

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MinIO · MinIOversion=< RELEASE.2025-04-03T14-56-28Z

Published CVSS scores

8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
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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