MinIO has an Unauthenticated Object Write via Query-String Credential Signature Bypass in Unsigned-Trailer Uploads

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-41145: 0.35% estimated exploitation activity in the next 30 days; percentile 28.63 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact What kind of vulnerability is it? Who is impacted? An authentication bypass vulnerability in MinIO's STREAMING-UNSIGNED-PAYLOAD-TRAILER code path allows any user who knows a valid access key to write arbitrary objects to any bucket without knowing the secret key or providing a valid cryptographic signature. Any MinIO deployment is impacted. The attack requires only a valid access key (the well-known default minioadmin, or any key with WRITE permission on a bucket) and a target bucket name. PutObjectHandler and PutObjectPartHandler call newUnsignedV4ChunkedReader with a signature verification gate based solely on the presence of the Authorization header: Meanwhile, isPutActionAllowed extracts credentials from either the Authorization header or the X-Amz-Credential query parameter, and trusts whichever it finds. An attacker omits the Authorization header and supplies credentials exclusively via the query string. The signature gate evaluates to false, doesSignatureMatch is never…

Published by the source

14 Apr 2026, 23:40 UTC

Last modified by the source

5 May 2026, 15:43 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-hv4r-mvr4-25vw

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# Patch Next advisory brief: CVE-2026-41145

Advisory: MinIO has an Unauthenticated Object Write via Query-String Credential Signature Bypass in Unsigned-Trailer Uploads
IDs: CVE-2026-41145, GHSA-hv4r-mvr4-25vw
Record: https://patchnext.com/advisories/cve-2026-41145 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/minio/minio: affected >= 0.0.0-20230506025312-76913a9fd5c6, <= 0.0.0-20260212201848-7aac2a2c5b7c

## Suggested inspection (read-only)
- Go github.com/minio/minio: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/minio/minio.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-hv4r-mvr4-25vw (GitHub-reviewed advisory GHSA-hv4r-mvr4-25vw lists affected ranges: Go github.com/minio/minio >=0.0.0-20230506025312-76913a9fd5c6 <=0.0.0-20260212201848-7aac2a2c5b7c)

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