SeaweedFS up to 4.39 TUS Resumable-Upload privileges management

Summaryinfo

A vulnerability labeled as critical has been found in SeaweedFS up to 4.39. The affected element is an unknown function of the component TUS Resumable-Upload Handler. Executing a manipulation can lead to privileges management. This vulnerability appears as CVE-2026-77368. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in SeaweedFS up to 4.39. This vulnerability affects an unknown part of the component TUS Resumable-Upload Handler. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

SeaweedFS is a distributed storage system for files and blobs. In version 4.39, the filer's TUS resumable-upload handler checks JWT allowed_prefixes scoping only when a session is created, letting a low-privilege tenant hijack another tenant's upload session to write content to filer paths their own token forbids. The HEAD, PATCH, and DELETE verbs that act on an existing session by its id never verify that the session's stored target path falls within the caller's allowed prefixes, so a tenant who obtains another upload's session identifier can PATCH attacker bytes into it and, on completion, have the file land at the victim's out-of-scope path. The same token can also DELETE other tenants' sessions and HEAD them to read upload progress and size, defeating the JWT prefix isolation. This vulnerability only affects deployments that configure filer JWT signing and have TUS uploads enabled. This issue is fixed in version 4.40.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-77368 since 08/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1068.

Upgrading to version 4.40 eliminates this vulnerability.

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Productinfo

Name

• SeaweedFS

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20
• 4.21
• 4.22
• 4.23
• 4.24
• 4.25
• 4.26
• 4.27
• 4.28
• 4.29
• 4.30
• 4.31
• 4.32
• 4.33
• 4.34
• 4.35
• 4.36
• 4.37
• 4.38
• 4.39

Website

• Product: https://github.com/seaweedfs/seaweedfs/

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