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CVE-2026-77298— SeaweedFS S3 OIDC Bearer authentication bypasses IAM role trust policy

Quick assessment

Affected
seaweedfs seaweedfs
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SeaweedFS 是一个用于文件和对象存储的分布式存储系统。在 4.39 及更早版本中，S3 API 允许将外部 OIDC JWT 令牌直接通过 Authorization 请求头发送，并将其映射到某个 IAM 角色，但并未强制校验该角色的信任策略，因此联合身份（federated user）可以获取其本不应被允许的角色。 标准的 STS AssumeRoleWithWebIdentity 路径会在角色的信任策略不信任该令牌的 OIDC 提供者时拒绝该令牌；而 S3 直接 Bearer 认证路径仅校验令牌本身的有

CVSS 8.7 · High
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I. Basic Information for CVE-2026-77298

Vulnerability Information
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Vulnerability Title
SeaweedFS S3 OIDC Bearer authentication bypasses IAM role trust policy
Source: CVE Program / CVE List V5
Vulnerability 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
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
seaweedfs seaweedfs < 4.40 -

II. Public POCs for CVE-2026-77298

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Qwen3.6-35B-A3B · 8132 chars
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III. Intelligence Information for CVE-2026-77298

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Patches & Fixes for CVE-2026-77298 (1)

Vendor Advisories for CVE-2026-77298 (1)

Same Patch Batch · seaweedfs · 2026-08-26 · 4 CVEs total

CVE-2026-77317 8.1 HIGH SeaweedFS: SFTP path ACL literal prefix match permits cross-tenant file read and overwrite
CVE-2026-77368 7.6 HIGH SeaweedFS: Authenticated Cross-Prefix IDOR in Filer TUS Handler Enables Arbitrary Write to
CVE-2026-77611 7.1 HIGH SeaweedFS: Authenticated S3 object-scope bypass in PutObjectAcl allows overwriting a diffe

IV. Related Vulnerabilities

Same product: seaweedfs
Same vendor: seaweedfs
Same weakness: CWE-863

V. Comments for CVE-2026-77298

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