SeaweedFS is a distributed storage system for files and blobs. In versions 4.39 and earlier, the S3 API accepts an external OIDC JWT sent directly in the Authorization header and maps it to an IAM role without enforcing that role's trust policy, so a federated user can assume a role they are not permitted to hold. The standard STS AssumeRoleWithWebIdentity path rejects such a token when the role's trust policy does not trust the token's federated provider, but the direct S3 bearer path validates only the token itself and then authenticates as the mapped role and evaluates that role's attached S3 permissions. As a result, a valid OIDC user whose token would be denied the role through STS can obtain the role's S3 access, including object read, write, and delete, by presenting the raw OIDC JWT directly to the S3 API. This issue is fixed in version 4.40
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History

Thu, 27 Aug 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Seaweedfs
Seaweedfs seaweedfs
Vendors & Products Seaweedfs
Seaweedfs seaweedfs

Wed, 26 Aug 2026 22:00:00 +0000

Type Values Removed Values Added
Description SeaweedFS is a distributed storage system for files and blobs. In versions 4.39 and earlier, the S3 API accepts an external OIDC JWT sent directly in the Authorization header and maps it to an IAM role without enforcing that role's trust policy, so a federated user can assume a role they are not permitted to hold. The standard STS AssumeRoleWithWebIdentity path rejects such a token when the role's trust policy does not trust the token's federated provider, but the direct S3 bearer path validates only the token itself and then authenticates as the mapped role and evaluates that role's attached S3 permissions. As a result, a valid OIDC user whose token would be denied the role through STS can obtain the role's S3 access, including object read, write, and delete, by presenting the raw OIDC JWT directly to the S3 API. This issue is fixed in version 4.40
Title SeaweedFS S3 OIDC Bearer authentication bypasses IAM role trust policy
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-27T14:17:48.966Z

Reserved: 2026-08-20T19:17:14.375Z

Link: CVE-2026-77298

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-26T22:16:29.570

Modified: 2026-08-27T17:20:22.050

Link: CVE-2026-77298

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-26T23:45:03Z

Weaknesses