CVE-2026-77611Public exploitNetwork attack vectorHinoki check available

Authenticated object overwrite via wrong-directory ACL update

Published Aug 26, 2026 · Updated Aug 27, 2026

Incorrect authorization in SeaweedFS before 4.40 allows remote authenticated users to overwrite out-of-scope S3 objects via PutObjectAcl. PutObjectAclHandler authorizes the requested nested key but sends the full entry to UpdateEntry at the bucket root instead of the key's parent directory. Exploitation requires valid S3 credentials with write and ACL rights to a nested key; a same-basename root object can have its content, metadata, owner, and ACL replaced.

CVSS severity7.1
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Incorrect authorization in SeaweedFS before 4.40 allows remote authenticated users to overwrite out-of-scope S3 objects via PutObjectAcl. PutObjectAclHandler authorizes the requested nested key but sends the full entry to UpdateEntry at the bucket root instead of the key's parent directory. Exploitation requires valid S3 credentials with write and ACL rights to a nested key; a same-basename root object can have its content, metadata, owner, and ACL replaced.

The record

CVE
CVE-2026-77611
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
SeaweedFS
Product
SeaweedFS
Classifications
CWE-863, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.40

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SeaweedFS · SeaweedFSversion=< 4.40

Published CVSS scores

7.1GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1565.001Stored Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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