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CVE-2026-77611— SeaweedFS: Authenticated S3 object-scope bypass in PutObjectAcl allows overwriting a different object with the same basename

Quick assessment

Affected
seaweedfs seaweedfs
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
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 Blob 存储的分布式存储系统。在 4.40 版本之前，一个具有作用域限定为嵌套对象键的已认证 S3 主体，可以通过对其有权限访问的键调用 PutObjectAcl，从而覆盖作用域之外的其他对象。处理程序针对请求中的嵌套键进行授权，但随后将更新后的条目写回到桶根目录，而不是键实际的父目录，因此在 allowed/protected.txt 上的 ACL 更改实际上被应用到了桶根目录下的 protected.txt。由于该更新携带了完整的条目（而不仅仅是 ACL 元数据），现有的

CVSS 7.1 · High
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I. Basic Information for CVE-2026-77611

Vulnerability Information
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Vulnerability Title
SeaweedFS: Authenticated S3 object-scope bypass in PutObjectAcl allows overwriting a different object with the same basename
Source: CVE Program / CVE List V5
Vulnerability Description
SeaweedFS is a distributed storage system for files and blobs. In versions prior to 4.40, an authenticated S3 principal with permissions scoped to a nested object key can overwrite a different object outside that scope by calling PutObjectAcl on the key it is allowed to access. The handler authorizes the request against the requested nested key but then writes the updated entry back to the bucket root rather than the key's actual parent directory, so an ACL change on allowed/protected.txt is instead applied to protected.txt at the bucket root. Because the update carries the full entry rather than only ACL metadata, an existing target object is overwritten with the content, metadata, owner information, and ACL of the scoped object, bypassing the object-level action scoping configured through the static S3 identity file. This issue is fixed in version 4.40.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
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-2026-77611

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III. Intelligence Information for CVE-2026-77611

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Patches & Fixes for CVE-2026-77611 (1)

Vendor Advisories for CVE-2026-77611 (1)

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

CVE-2026-77298 8.7 HIGH SeaweedFS S3 OIDC Bearer authentication bypasses IAM role trust policy
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

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-77611

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