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.

SeaweedFS is a distributed storage system for files and blobs. In versions from 3.88 through 4.39, the SFTP server evaluates configured path permissions with a literal string-prefix comparison, so a user scoped to a path is also granted the same access to any sibling path whose name merely begins with the same characters. A user granted access to /tenants/alice therefore also matches /tenants/alice-archive, /tenants/alice2, and similar siblings, because the check does not require a path-component boundary. An authenticated low-privilege SFTP user with a root home directory and narrow path permissions can thereby cross the configured ACL boundary to read another tenant's files, and to overwrite them if granted write, all through the documented SFTP service with its own valid credentials. This issue is fixed in version 4.40.

SeaweedFS is a distributed storage system for files and blobs. In versions 4.39 and earlier, the S3 API accepts an external OIDC JWT sent directly in the Authorization header and maps it to an IAM role without enforcing that role's trust policy, so a federated user can assume a role they are not permitted to hold. The standard STS AssumeRoleWithWebIdentity path rejects such a token when the role's trust policy does not trust the token's federated provider, but the direct S3 bearer path validates only the token itself and then authenticates as the mapped role and evaluates that role's attached S3 permissions. As a result, a valid OIDC user whose token would be denied the role through STS can obtain the role's S3 access, including object read, write, and delete, by presenting the raw OIDC JWT directly to the S3 API. This issue is fixed in version 4.40

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.

SeaweedFS is a distributed storage system. Prior to 4.24, the weed/server/filer_server_handlers.go allowed_prefixes authorization check used strings.HasPrefix on raw path strings, so a filer JWT scoped to /tenant1 also authorized sibling paths such as /tenant1234, /tenant1-old, and /tenant1backup, enabling cross-tenant reads and writes with a valid scoped token. This issue is fixed in version 4.24.

SeaweedFS is a distributed storage system. Prior to 4.24, the filer registers the SeaweedIdentityAccessManagement gRPC service without mandatory authentication when jwt.filer_signing.key is unset, allowing any client that can reach the filer gRPC port to invoke CreateUser, CreateAccessKey, PutPolicy, and related IAM RPCs to mint credentials and gain S3 administrative control. This issue is fixed in versions 4.24.

SeaweedFS is a distributed storage system. Prior to 4.24, VolumeServer.FetchAndWriteNeedle in weed/server/volume_grpc_remote.go fetches a caller-supplied remote endpoint through weed/remote_storage/s3/s3_storage_client.go and writes the response into a needle. The RPC performs no authentication and no target validation, allowing anyone who can reach a volume server's gRPC port to cause requests to arbitrary hosts, including loopback, link-local, RFC 1918, and cloud metadata endpoints such as 169.254.169.254, and read the response. On cloud deployments, this can disclose instance metadata and IAM credentials and reach otherwise unexposed internal services. The volume server gRPC plane is unauthenticated by default, and configuring documented JWT signing keys does not protect this RPC. This issue is fixed in version 4.24.

SeaweedFS is a distributed storage system. In versions 4.08 through 4.33, requests signed with SigV4 service s3tables are routed to the S3Tables management API where authorization collapses account-less S3 identities into the shared admin account and fails open, allowing an authenticated low-privileged S3 user to enumerate administrator-owned table bucket names and ARNs. This issue is fixed in version 4.34.

SeaweedFS is a distributed storage system. Prior to 4.34, the S3 API gateway does not reject dot-dot path segments in the X-Amz-Copy-Source header used by CopyObject and UploadPartCopy, allowing an authenticated identity scoped to one bucket to read objects from other buckets through server-side copy. This issue is fixed in version 4.34.

SeaweedFS before 4.34 contains a path traversal vulnerability in the S3 gateway DeleteMultipleObjectsHandler that allows authenticated S3 principals with write access to a single bucket to delete arbitrary objects in other tenants' buckets by supplying object keys containing ../ sequences in the DeleteObjects XML request body. Attackers can bypass authorization controls through a confused deputy condition, as the validateRequestPath middleware only inspects URL-captured path variables and never examines request-body keys, allowing the filer path to collapse directory traversal sequences and resolve deletions outside the authorized bucket.