CVE-2026-77611

Status: DeferredHigh (7.1)—

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.

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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.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Base score: 7.1

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.38%
Percentile among all scored CVEs: 30
Score date: 10/4/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1210 Exploitation of Remote Serviceslateral movement85 %
Primary impactT1565.001 Stored Data Manipulationimpact90 %
Secondary impactT1078.001 Default Accountsstealth · persistence · privilege escalation · initial access75 %

Explotación remota de servicio S3 por usuario autenticado (PR:L). Impacto: sobrescritura de objetos fuera del alcance autorizado y manipulación de ACL/metadatos de otros usuarios.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Vulnerability Scanning Threat Intelligence Program Restrict File and Directory Permissions Privileged Account Management Password Policies Remote Data Storage

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Seaweedfs — Seaweedfs^AI

CWEs

CWE-863

References

Raw JSON (NVD)

Show

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  "published": "2026-08-26T22:16:30.007",
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  "lastModified": "2026-09-09T21:09:13.080",
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