SeaweedFS: Authenticated S3 object-scope bypass in PutObjectAcl allows overwriting a different object with the same basename (CVE-2026-77611) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-77611

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

Answer in brief

CVE-2026-77611 records a Unknown severity vulnerability in SeaweedFS: Authenticated S3 object-scope bypass in PutObjectAcl allows overwriting a different object with the same basename. The current sources do not mark it as known exploited. The current feed maps seaweedfs/seaweedfs (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 26, 2026Updated Aug 26, 2026Source checked Aug 26, 2026First seen by HOL Aug 26, 2026Material review Aug 26, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps seaweedfs/seaweedfs (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
seaweedfs/seaweedfsgeneric	< 4.40	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for seaweedfs/seaweedfs.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 26, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.