GHSA-rm5c-5x2p-48wr Klever-Go KVM: Unauthenticated remote node crash (nil-pointer DoS) in klever-go P2P transaction interceptor (txVersionChecker nil RawData) - potential chain halt

• Go github.com/klever-io/klever-go: >= 1.7.14, < 1.7.18 → fixed in 1.7.18

Summary Every transaction gossiped on the klever-go P2P network is decoded and validated synchronously inside the libp2p pubsub topic-validator callback. The validator `txVersionChecker.CheckTxVersion` dereferences `tx.RawData.Version` with no nil check. A protobuf `Transaction` whose embedded `RawData` sub-message is omitted decodes to `RawData == nil`, so validating it triggers a nil-pointer panic. The libp2p pubsub callback, the underlying go-libp2p-pubsub validation worker, and klever's own `network/p2p` layer install no `recover()`, so the panic propagates and crashes the entire node process. The attacker payload is a 3-byte protobuf message; no validator key, stake, funds, or on-chain account is required. Aimed at enough of the BLS validator set, repeated delivery halts block production (chain halt). Affected component • Root cause: `core/versioning/txVersionChecker.go:22` • Reached via: `core/process/transaction/interceptedTransaction.go:203` (integrity) and `:154` (CheckValidity) • Production tx-topic path: `core/process/interceptors/multiDataInterceptor.go:171` and `:223` • Unprotected caller: `network/p2p/libp2p/netMessenger.go` `pubsubCallback` (no recover) • Topic wiring: `core/process/factory/interceptorscontainer/baseInterceptorsContainerFactory.go` (`createOneTxInterceptor`) Details Synchronous validation path, no recovery at any frame: ``` libp2p pubsubCallback network/p2p/libp2p/netMessenger.go (no recover) -> MultiDataInterceptor.ProcessReceivedMessage core/process/interceptors/multiDataInterceptor.go:171 -> interceptedData(...) core/process/interceptors/multiDataInterceptor.go:223 -> InterceptedTransaction.CheckValidity core/process/transaction/interceptedTransaction.go:154 -> integrity() core/process/transaction/interceptedTransaction.go:203 -> txVersionChecker.CheckTxVersion(tx) core/versioning/txVersionChecker.go:22 panic return process.ErrInvalidTransactionVersion } return nil } ``` `integrity()` calls `CheckTxVersion` as its very first statement, before any `RawData` nil-check, and `CheckValidity()` runs before the whitelist / originator- election gate in the interceptor, so node-role and whitelist restrictions do not protect this path. Preconditions • Attacker runs an ordinary libp2p peer reachable to the target via normal peering / kad-dht discovery on the `transactions` gossip topic. • Production runs with `withMessageSigning = true`, which only requires the gossip message to be signed by the attacker's OWN libp2p peer key (a self-generated identity; NOT a validator key, NOT funded, NOT authorized). • No special config or feature flag; the tx interceptor is built unconditionally and subscribes to `transactions` on every node. Impact • Deterministic, immediate crash of any targeted node (validator, sentry, or observer) from a single ~3-byte message. • Gossipsub validates before relaying, so the victim does not forward the crashing message; the attacker delivers it directly to each target (one tiny message/node). • With auto-restart (systemd), re-sending sustains the outage. • Directed at > 1/3 of the BLS validator set, this prevents consensus and halts the chain. • NOTE: the HTTP `POST /transaction/send` path is NOT crash-exploitable - the REST server uses `gin.Default()` (Recovery middleware) and returns HTTP 500. The exploitable vector is the P2P interceptor. Exploit cost / attack complexity • Cost: negligible (one self-signed libp2p peer; 3-byte payload; no gas/capital). • Complexity: LOW. Unauthenticated, remote, deterministic. PoC-Source Scenario • Build the malicious transaction as it appears on the wire: a protobuf `Transaction` with `RawData` omitted (plus a throwaway `Signature` so the batch entry looks like a real tx). With the production proto marshalizer this encodes to 3 bytes (`12 01 78`) and round-trips back to `RawData == nil`. • Feed it through the REAL production interceptors. The `transactions` gossip topic is served by a `MultiDataInterceptor` (`baseInterceptorsContainerFactory.go`, `createOneTxInterceptor`); the test wraps the tx in a `Batch` exactly like a bulk-tx gossip message and calls `ProcessReceivedMessage`, which is precisely what the panic-free libp2p `pubsubCallback` invokes in production. A second test drives the generic `SingleDataInterceptor` to show the bug is in the shared validation chain. • The data factory is a faithful copy of the production `interceptedTxDataFactory.Create`: it builds a genuine `*InterceptedTransaction`. No validation behavior is stubbed; only leaf crypto/marshal helpers use the repo's own in-tree mocks. The panic occurs on the first line of `integrity()`, upstream of any mock. How to run 1. `git clone https://github.com/klever-io/klever-go && cd klever-go` (Go toolchain matching go.mod `go 1.25.7`; verified locally on go1.26.3.) 2. Save the source below as `core/process/interceptors/poc_nil_rawdata_dos_test.go`. 3. Run either (separately - the first panic aborts the test binary): • Production tx-topic path: `go test ./core/process/interceptors/ -run TestPoC_NilRawData_MultiDataInterceptor -v` • Generic path: `go test ./core/process/interceptors/ -run TestPoC_NilRawData_SingleDataInterceptor -v` • Dependencies: none beyond the repo's own go.mod (uses in-repo mocks only). Full PoC source (`poc_nil_rawdata_dos_test.go`): ```go // Target component: klever-go P2P transaction interceptor (network availability) // core/process/transaction/interceptedTransaction.go // core/versioning/txVersionChecker.go:22 // Vulnerability type: Unauthenticated remote Denial-of-Service (nil-pointer panic / chain-wide node crash) // CWE-476 (NULL Pointer Dereference) reached from untrusted P2P input. // // Summary: // Every gossiped transaction is decoded and validated synchronously inside the // libp2p pubsub topic-validator callback // (network/p2p/libp2p/netMessenger.go -> pubsubCallback). That callback has NO // recover(). The validation chain is: // // (Multi|Single)DataInterceptor.ProcessReceivedMessage // -> InterceptedTransaction.CheckValidity // -> integrity() // -> txVersionChecker.CheckTxVersion(tx) // tx.RawData.Version core/process/interceptors/poc_nil_rawdata_dos_test.go // 3) go test ./core/process/interceptors/ -run TestPoC_NilRawData -v // // Expected output: // The test process aborts with: // panic: runtime error: invalid memory address or nil pointer dereference // ... core/versioning.(*txVersionChecker).CheckTxVersion ... txVersionChecker.go:22 // ... InterceptedTransaction.integrity ... -> CheckValidity // ... (Multi|Single)DataInterceptor.ProcessReceivedMessage // i.e. the crash originates from the interceptor's synchronous message-handling frame, // exactly where the panic-free libp2p pubsub callback would call it in production. // // Dependencies: none beyond the repo's own go.mod (uses in-repo mocks only). package interceptors_test import ( "testing" "github.com/klever-io/klever-go/common/mock" "github.com/klev…