filecoin-pin: Unbounded DAG pinning can exhaust server resources

Summary

The IPFS Pinning Service API implementation accepts a caller-controlled CID through POST /pins, queues background processing, and then recursively fetches the full DAG with helia.pins.add(cid). The route and background pinning path do not enforce a request rate limit, per-user quota, maximum DAG byte count, maximum block count, traversal timeout, or concurrent pinning limit.

An authenticated caller, or an unauthenticated caller when the server is started with ALLOW_NO_AUTH=true, can submit one or more pins whose CIDs resolve to very large DAGs. The server writes fetched blocks to CAR files under carStoragePath and can consume disk, network, CPU, and libp2p resources until the process or host becomes unavailable.

Details

POST /pins validates only that the request body contains a syntactically valid CID string, then forwards it to the pin store:

• src/filecoin-pinning-server.ts:304-342 accepts the request, parses cid with CID.parse, and calls pinStore.pin(request.user, cidObject, parsed.options).
• src/filecoin-pin-store.ts:153-188 stores the pin as queued and schedules _processPinInBackground with setTimeout. There is no queue, semaphore, or global cap around this scheduling.
• src/filecoin-pin-store.ts:211-217 creates a per-pin Helia node and forwards caller-supplied origins.
• src/filecoin-pin-store.ts:260-274 walks the full DAG with for await (const pinnedCid of helia.pins.add(cid)).
• src/create-pinning-helia.ts:47-80 creates a libp2p/Helia node with the Bitswap block broker and no application-level resource limits.
• src/core/car/car-blockstore-base.ts:65-107 writes every fetched block and updates stats.totalSize only after writing.
• src/core/car/car-file-backend.ts:84-93 streams blocks to the CAR writer on disk.

The Helia node created for each pin has no bootstrap or mDNS configuration (src/create-pinning-helia.ts:57). A public CID alone may therefore not be fetchable unless the node can reach a content source. In practice, the API also accepts origins, so an attacker can supply a reachable attacker-controlled libp2p origin that serves a large DAG and cause the server to retrieve it.

Impact

Successful exploitation affects availability:

• Disk exhaustion from unbounded CAR files in carStoragePath.
• Network exhaustion from recursive Bitswap retrieval.
• CPU and memory pressure from concurrent libp2p/Helia pin operations.
• Service degradation or process failure for other users of the daemon.
• Operational cost and manual recovery burden from large partial CAR files.

The default daemon configuration reduces exposure because the server binds to localhost and refuses to start without an access token unless ALLOW_NO_AUTH=true. The finding is most significant when the daemon is exposed beyond localhost, when the token is shared across untrusted users, or when the no-auth mode is enabled.

PoC

curl -X POST "https://target.example/pins" \
  -H "Authorization: Bearer $ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "cid": "CID_OF_LARGE_DAG",
    "origins": ["/ip4/203.0.113.10/tcp/4001/p2p/ATTACKER_PEER_ID"],
    "meta": { "purpose": "resource-exhaustion-validation" }
  }'

Submitting many such requests concurrently accelerates resource pressure because each request schedules independent background processing.