GHSA-hvv7-hfrh-7gxj Nezha Monitoring: Nezha WebSocket server stream discloses cross-tenant server telemetry to authenticated members

• Go github.com/nezhahq/nezha: >= 1.4.0, < 1.14.15-0.20260517034128-05e5da253519 → fixed in 1.14.15-0.20260517034128-05e5da253519

Summary Any authenticated non-admin member can connect to the server-status WebSocket and receive telemetry for all servers, including servers owned by other users. The normal server list API filters objects by `HasPermission`, but the WebSocket stream treats the presence of any authenticated user as authorization for the full unfiltered server list. Details The server WebSocket route is registered under the optional-auth group in `cmd/dashboard/controller/controller.go:71-73`: ```go optionalAuth := api.Group("", optionalAuthMw) optionalAuth.GET("/ws/server", commonHandler(serverStream)) ``` `serverStream` treats any `CtxKeyAuthorizedUser` as a member, without checking admin role or per-server ownership, in `cmd/dashboard/controller/ws.go:123-139`: ```go u, isMember := c.Get(model.CtxKeyAuthorizedUser) var userId uint64 if isMember { userId = u.(*model.User).ID } ... stat, err := getServerStat(count == 0, isMember) ``` The authorization boolean is then used as a full/guest switch in `getServerStat` in `cmd/dashboard/controller/ws.go:160-184`: ```go if authorized { serverList = singleton.ServerShared.GetSortedList() } else { serverList = singleton.ServerShared.GetSortedListForGuest() } ... servers = append(servers, model.StreamServer{ ID: server.ID, Name: server.Name, PublicNote: utils.IfOr(withPublicNote, server.PublicNote, ""), DisplayIndex: server.DisplayIndex, Host: utils.IfOr(authorized, server.Host, server.Host.Filter()), State: server.State, CountryCode: countryCode, LastActive: server.LastActive, }) ``` For authenticated members, `GetSortedList()` returns all servers and `server.Host` is not filtered. There is no call to `server.HasPermission(c)`. The streamed response model in `model/server_api.go:5-20` includes server ID/name, public note, host details, runtime state, country code, last active time, and global online count. Host and state fields include platform version, agent version, CPU/GPU names, memory/disk/swap totals, architecture, virtualization, boot time, CPU load, memory/disk/swap usage, network transfer/speed, uptime, TCP/UDP/process counts, temperatures, and GPU utilization, as defined in `model/host.go:20-38` and `model/host.go:100-112`. The normal list endpoint has the expected object-level authorization. `GET /api/v1/server` is registered with `listHandler` in `cmd/dashboard/controller/controller.go:113`, and `listHandler` filters each returned object with `HasPermission` in `cmd/dashboard/controller/controller.go:263-291`: ```go filtered := filter(c, data) ... return slices.DeleteFunc(s, func(e E) bool { return !e.HasPermission(ctx) }) ``` The shared permission model in `model/common.go:44-56` allows admins to see all objects but restricts members to objects whose `UserID` matches their user ID: ```go if user.Role == RoleAdmin { return true } return user.ID == c.UserID ``` Mitigations checked: • Guests receive `GetSortedListForGuest()` and `Host.Filter()` output, but authenticated members bypass both guest restrictions. • `HideForGuest` only affects unauthenticated guests, not members. • The normal `/api/v1/server` list endpoint uses `listHandler` and is not affected in the same way. • No owner/admin filter is applied in the WebSocket path. Candidate score: 12/14 • Reachability: 2, default WebSocket API • Attacker control: 1, attacker controls authentication state and connection • Privilege required: 1, authenticated member • Sink impact: 2, cross-tenant sensitive telemetry disclosure • Mitigation weakness: 2, no object-level auth in the WebSocket path • Default exposure: 2, endpoint is part of default dashboard • Safe PoC feasibility: 2, can be verified with local users/servers or statically Exploitability gate: statically confirmed • Reachable source: `GET /api/v1/ws/server` • Default/common configuration: dashboard API exposed by default • Missing/bypassed mitigation: member-vs-guest check replaces object-level authorization • Impact-bearing sink: WebSocket response includes unfiltered all-server telemetry • Safe proof: static source-to-sink proof; full runtime test blocked locally by unavailable Go 1.26 toolchain • Affected version evidence: confirmed at commit `85b0dd2992733037b019442caffc6c049ba937dd` (`v2.0.7-1-g85b0dd2`) • Variant review: normal server list endpoint and guest filtering were checked PoC Static local PoC steps: 1. Start Nezha with two non-admin users and at least one server assigned to each user. 2. Authenticate as user A. 3. Connect to the WebSocket endpoint with user A's token, for example: ```http GET /api/v1/ws/server HTTP/1.1 Host: 127.0.0.1:8008 Cookie: nz-jwt= Upgrade: websocket Connection: Upgrade ``` 4. Observe that the JSON messages contain entries for all servers from `singleton.ServerShared.GetSortedList()`, including servers whose `UserID` does not match user A. 5. Compare with `GET /api/v1/server` using the same token; that route is filtered through `listHandler`/`HasPermission` and should only return user A's own servers. Cleanup: no persistent state is created by the WebSocket connection. Local dynamic confirmation note: the full project test/runtime could not be executed in this audit environment because the repository requires Go 1.26 and the local toolchain reported `go: download go1.26 for linux/amd64: toolchain not available`. Impact This is an authenticated horizontal information disclosure. A low-privileged member can continuously monitor other users' server inventory and live telemetry, including host platform details, agent versions, CPU/GPU details, resource usage, traffic counters, country code, and last-active timestamps. This may expose infrastructure composition, usage patterns, and operational state across tenants. Suggested remediation Apply object-level authorization in `getServerStat` for authenticated non-admin users. For each server in the stream, include it only if the current user is admin or `server.UserID` matches the authenticated user. Keep guest filtering and host redaction for unauthenticated users.