CVE-2026-97731 — HIGH (7.1)

Vulnerability Description

MinIO through 7aac2a2 does not verify that every x-amz-* header present on a request also appears in the client-supplied X-Amz-SignedHeaders list. extractSignedHeaders() in cmd/signature-v4-utils.go iterates only the claimed list and never enumerates the headers that actually arrived, and thus a header that arrives unsigned is neither hashed into the canonical request nor rejected. Because cmd/api-router.go dispatches CopyObject on the presence of x-amz-copy-source alone, the holder of a presigned PUT URL scoped to a single object can add that header to the unmodified URL and cause a server-side copy, executed as the signer, of any object the signing key can read. A grant to write one object becomes a read of every bucket that key can reach. Amazon S3 rejects the equivalent request with HTTP 403 AccessDenied. The minio/minio GitHub repository was archived in April 2026; pgsty/silo before 1233254 is also affected.

CVSS Score

7.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

LOW

Availability

NONE

Related Weaknesses (CWE)

CWE-347

References

FAQ

What is CVE-2026-97731?

CVE-2026-97731 is a vulnerability with a CVSS score of 7.1 (HIGH). MinIO through 7aac2a2 does not verify that every x-amz-* header present on a request also appears in the client-supplied X-Amz-SignedHeaders list. extractSignedHeaders() in cmd/signature-v4-utils.go i...

How severe is CVE-2026-97731?

CVE-2026-97731 has been rated HIGH with a CVSS base score of 7.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-97731?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.