CVE-2026-97731

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-09-30
Weakness: CWE-347

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.

References

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