GHSA-q6xx-5vr8-p898: Github.com/nezhahq/nezha Nezha Vulnerable To Cross-tenant Terminal/file-manager Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q6xx-5vr8-p898",
  "modified" : "2026-06-26T22:31:41Z",
  "published" : "2026-06-26T22:31:41Z",
  "aliases" : [ ],
  "summary" : "Nezha vulnerable to cross-tenant terminal/file-manager session hijack via WebSocket stream UUID without ownership check",
  "details" : "### Summary\n\nIn nezha **v1.14.13–v1.14.14** and **v2.0.0–v2.0.9**, the WebSocket endpoints `GET /ws/terminal/:id` and `GET /ws/file/:id` authenticate the caller only by the presence of a valid stream UUID, with no ownership check tying that UUID to the user who created the stream. Any authenticated dashboard user (including a `RoleMember`) who learns a live stream UUID can attach to the session and gain interactive shell access or full file-manager control on the target server — i.e. cross-tenant RCE.\n\nThis was silently fixed in commit [`6661d6a`](https://github.com/nezhahq/nezha/commit/6661d6a7fc1c269f55c7f4e775082ad23fbe0f54) (2026-05-18, shipped in v2.0.10). At submission time no public CVE/GHSA covers this fix, so operators of v1.14.x and pre-v2.0.10 v2.x deployments have no signal that they are running vulnerable code.\n\n### Details\n\n**Stream allocation — `service/rpc/io_stream.go` (v2.0.9):**\n\n```go\nfunc (s *NezhaHandler) CreateStream(streamId string) {\n    s.ioStreamMutex.Lock()\n    defer s.ioStreamMutex.Unlock()\n\n    s.ioStreams[streamId] = &ioStreamContext{\n        userIoConnectCh:  make(chan struct{}),\n        agentIoConnectCh: make(chan struct{}),\n    }\n}\n```\n\nNo creator is bound to the stream.\n\n**Stream attach — `cmd/dashboard/controller/terminal.go` (v2.0.9):**\n\n```go\n// @Router /ws/terminal/{id} [get]\nfunc terminalStream(c *gin.Context) (any, error) {\n    streamId := c.Param(\"id\")\n    if _, err := rpc.NezhaHandlerSingleton.GetStream(streamId); err != nil {\n        return nil, err\n    }\n    defer rpc.NezhaHandlerSingleton.CloseStream(streamId)\n    // ... WebSocket upgrade and bidirectional pipe ...\n}\n```\n\nThe only authorization check is `GetStream(streamId)` — \"does this UUID exist in the in-memory map\". `getUid(c)` is never compared against the user who called `createTerminal`. The same pattern is present in `fmStream(c)` in `cmd/dashboard/controller/fm.go`.\n\n**Where the UUID leaks:**\n\n`createTerminal` returns the UUID to the legitimate client, which then opens `wss://<dashboard>/ws/terminal/<UUID>`. As a URL path component the UUID is exposed via:\n\n- Reverse-proxy access logs (nginx, Caddy, Cloudflare).\n- Referer headers when the page embeds external resources or error reporters.\n- Browser history / bookmark sync.\n- Frontend telemetry (Sentry, Bugsnag) breadcrumbs that include the WebSocket URL.\n- Any shared-tenant or multi-operator log viewer.\n\nAny authenticated user with access to one of these side channels can attach to a live session.\n\n### PoC\n\n1. Deploy nezha v2.0.9. Add at least one server. Configure two accounts: `admin` (RoleAdmin, owns the server) and `member` (RoleMember, no access to that server).\n2. As `admin`, open the web terminal for the server. The browser opens `wss://<dashboard>/ws/terminal/<UUID>`. Capture this UUID from the network inspector, server access log, or `Referer` header.\n3. From a separate session logged in as `member`, open `wss://<dashboard>/ws/terminal/<UUID>` (same UUID). The member's WebSocket attaches to the same `ioStreamContext` because `terminalStream` only checks `GetStream(streamId)` — no ownership check.\n4. The member can now read the admin's shell output and inject keystrokes, achieving shell-level RCE on the target server, with no visible signal to the legitimate session owner.\n\nSame flow works against `/ws/file/:id` (file-manager hijack: arbitrary read/write on the target server's filesystem).\n\n### Impact\n\n- **Severity**: Critical. Interactive RCE on a server administered by another user, with no audit signal to the rightful session owner.\n- **Attack complexity**: Low. The attacker needs an authenticated dashboard account (which any `RoleMember` is) and one captured UUID from a side channel.\n- **Confidentiality / Integrity / Availability**: all High. `/ws/file/:id` exposes arbitrary read+write on the target filesystem; `/ws/terminal/:id` is a full shell.\n\nThis is the same impact tier as CVE-2026-46716 (cross-tenant cron RCE) and arguably worse, because the entry point is a passively-leaked URL rather than an authenticated POST — attackers do not need direct dashboard interaction once the UUID is leaked through logs or telemetry.\n\n### Fix reference\n\nAlready fixed in master by commit [`6661d6a`](https://github.com/nezhahq/nezha/commit/6661d6a7fc1c269f55c7f4e775082ad23fbe0f54) (\"fix(rpc): bind io_stream sessions to creator to prevent terminal/fm hijack\"):\n\n- `CreateStream` now accepts a `creatorUserID uint64` and stores it on the `ioStreamContext`.\n- New `IsStreamAuthorizedForUser(streamId, userID, isAdmin)` helper.\n- `terminalStream` and `fmStream` call this helper **before** the WebSocket upgrade and **before** the `defer CloseStream(streamId)`, so a rejected attempt does not tear down a legitimate stream.\n\nShipped in v2.0.10 (2026-05-19). The v1.14 line has not received a backport.\n\n### Why this advisory\n\nThe fix landed silently. The other May 17–21 fixes received public GHSAs (GHSA-99gv-2m7h-3hh9, GHSA-rxf6-wjh4-jfj6, GHSA-hvv7-hfrh-7gxj, GHSA-w4g9-mxgg-j532, GHSA-6x26-5727-rrm9, GHSA-4g6j-g789-rghm) covering cron RCE, AlertRule trigger, telemetry leak, notification SSRF, DDNS SSRF, and agent forge-results respectively — but none cover the terminal / file-manager session hijack. This advisory closes that gap so operators of v1.14.x and v2.0.0–v2.0.9 know to upgrade.\n\n### Recommended action\n\n- Publish this GHSA so v2.x operators below v2.0.10 see the alert in their dependency scanners.\n- Either backport `6661d6a` to a v1.14.15 release, or mark the v1.14 line end-of-life in `SECURITY.md` so operators understand the support boundary.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/nezhahq/nezha"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.14.13"
      }, {
        "last_affected" : "1.14.14"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/nezhahq/nezha"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.0.10"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.0.9"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nezhahq/nezha/security/advisories/GHSA-q6xx-5vr8-p898"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nezhahq/nezha"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T22:31:41Z",
    "nvd_published_at" : null
  }
}