CVE-2026-77368Public exploitNetwork attack vector

Cross-tenant writes via unscoped TUS session verbs

Published Aug 26, 2026 · Updated Aug 27, 2026

Authorization bypass in SeaweedFS 4.39 allows remote authenticated users to write data outside permitted filer prefixes via TUS. The filer TUS handler leaves the scoped-path list empty for HEAD, PATCH, and DELETE, so JWT prefix checks approve a known session ID without checking its stored target path. Exploitation requires filer JWT signing, TUS uploads, a valid low-privilege write token, and another tenant's session ID; it also exposes upload metadata or cancels the session.

CVSS severity7.6
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in SeaweedFS 4.39 allows remote authenticated users to write data outside permitted filer prefixes via TUS. The filer TUS handler leaves the scoped-path list empty for HEAD, PATCH, and DELETE, so JWT prefix checks approve a known session ID without checking its stored target path. Exploitation requires filer JWT signing, TUS uploads, a valid low-privilege write token, and another tenant's session ID; it also exposes upload metadata or cancels the session.

The record

CVE
CVE-2026-77368
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
SeaweedFS
Product
SeaweedFS
Classifications
CWE-639, T1190
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=>= 4.39, < 4.40

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SeaweedFS · SeaweedFSversion=>= 4.39, < 4.40

Published CVSS scores

7.6GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-639Authorization Bypass Through User-Controlled Key
T1190Exploit Public-Facing Application

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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