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EUVD-2026-350861

fkie_cve-2026-52880

Klever-Go is the Go implementation of the Klever blockchain protocol. Versions from 1.7.14 through 1.7.17 are vulnerable to a remotely triggerable denial of service. Both REST APIs are started with the Gin Engine.Run convenience method, which serves requests through Go's default HTTP server with no ReadHeaderTimeout, ReadTimeout, or MaxHeaderBytes configured. As a result, incoming connections that never complete their request headers are held open indefinitely. When a REST listener is reachable beyond localhost through the documented all-interface bind or a Docker port-publish deployment, a single unauthenticated client can open many slow-header connections and hold them open until server file descriptors are exhausted, preventing the API from accepting new connections. This renders the REST API unavailable to legitimate clients. This issue is fixed in version 1.7.18.

GHSA-w4c6-7r69-w7j9 — klever-go: REST API slow-header connection exhaustion via Gin Engine.Run

Affected: Go: github.com/klever-io/klever-go

### Summary

The Klever seednode REST API starts a Gin engine with `Engine.Run(restAPIInterface)`. In Gin v1.9.1, `Engine.Run` calls Go's default `http.ListenAndServe`, which constructs an HTTP server without application-level `ReadHeaderTimeout`, `ReadTimeout`, or `MaxHeaderBytes` limits.

An unauthenticated client that can reach a REST listener bound with Klever's documented `--rest-api-interface :8080` all-interface option can hold incomplete HTTP headers open indefinitely. In a local proof against the real `cmd/seednode/api.Start` path on `v1.7.17`, 120 slow-header connections caused 20/20 legitimate `/log` probes to fail with `accept: too many open files`. A fixed control using the same Gin router behind an explicit `http.Server` with `ReadHeaderTimeout`, `ReadTimeout`, and `MaxHeaderBytes` retained 0 slow connections and served 20/20 probes.

This report is distinct from the P2P advisories and from my direct-message goroutine report. This finding concerns Klever-owned HTTP REST startup code (`cmd/seednode/api` and `network/api`) using Gin `Engine.Run` without server-level header deadlines. It does not depend on `MultiDataInterceptor`, `Batch.Decompress`, libp2p, malformed P2P messages, or direct-message goroutine spawning.

### Details

Seednode REST API, latest release `v1.7.17`:

- `cmd/seednode/api/api.go:17` defines `Start(restAPIInterface, marshalizer)`. - `cmd/seednode/api/api.go:18` creates `ws := gin.Default()`. - `cmd/seednode/api/api.go:23` returns `ws.Run(re…