Cross-bucket object disclosure via unsigned operation headers
Published Sep 25, 2026 · Updated Sep 25, 2026
Authorization bypass in MinIO through 7aac2a2 allows remote attackers holding a presigned PUT URL to copy objects readable by its signer. extractSignedHeaders() hashes only client-claimed headers, while the API router treats an added unsigned x-amz-copy-source header as a CopyObject request. Exploitation requires a valid presigned PUT URL, but a grant to write one object can expose objects across every bucket readable by the signing key.
Summary
What happened
Authorization bypass in MinIO through 7aac2a2 allows remote attackers holding a presigned PUT URL to copy objects readable by its signer. extractSignedHeaders() hashes only client-claimed headers, while the API router treats an added unsigned x-amz-copy-source header as a CopyObject request. Exploitation requires a valid presigned PUT URL, but a grant to write one object can expose objects across every bucket readable by the signing key.
The record
- CVE
- CVE-2026-97731
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- MinIO
- Product
- MinIO
- Classifications
- T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <=7aac2a2c5b7c882e68c1ce017d8256be2feea27f
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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