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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SeaweedFS团队开源的一款分布式网络存储文件系统。 SeaweedFS 4.40之前版本存在授权问题漏洞，该漏洞源于对PutObjectAcl请求处理不当，授权后将更新条目写回桶根而非键的实际父目录，导致越权覆盖其他对象，绕过对象级权限限制。

CVSS 7.1 · High EPSS 0.38% · P31

Affected Version Matrix 1

VendorProduct Version RangeStatus
seaweedfs seaweedfs < 4.40 affected
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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
Vulnerability Title
SeaweedFS 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
SeaweedFS是SeaweedFS团队开源的一款分布式网络存储文件系统。 SeaweedFS 4.40之前版本存在授权问题漏洞，该漏洞源于对PutObjectAcl请求处理不当，授权后将更新条目写回桶根而非键的实际父目录，导致越权覆盖其他对象，绕过对象级权限限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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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