Hoverfly is an open source API simulation tool. Prior to version 1.12.8, remote post-serve actions use `http.DefaultClient` without any timeout configuration. When the remote endpoint is unreachable or intentionally slow (accepts TCP connection but never responds), each triggered proxy request spawns a goroutine that blocks indefinitely on `http.DefaultClient.Do()`. An attacker can cause unbounded goroutine accumulation leading to memory exhaustion and process crash (OOM kill). Unlike local post-serve action execution, this requires no binary execution, only a URL pointing to a non-responsive endpoint. Version 1.12.8 patches the issue.

Affected: Go: github.com/SpectoLabs/hoverfly

### Summary:

Remote post-serve actions use `http.DefaultClient` without any timeout configuration. When the remote endpoint is unreachable or intentionally slow (accepts TCP connection but never responds), each triggered proxy request spawns a goroutine that blocks indefinitely on `http.DefaultClient.Do()`. An attacker can cause unbounded goroutine accumulation leading to memory exhaustion and process crash (OOM kill). Unlike local post-serve action execution, this requires no binary execution, only a URL pointing to a non-responsive endpoint.

### Details:

**1. Remote actions executed in goroutines without timeout (`core/hoverfly.go:224-228`):**

```go go postServeAction.Execute(result.Pair, journalIDChannel, hf.Journal) ```

Post-serve actions are executed in separate goroutines with no recovery wrapper.

**2. HTTP client has no timeout (`core/action/action.go:128-143`):**

```go req, err := http.NewRequest("POST", action.Remote, bytes.NewBuffer(pairViewBytes)) // ... resp, err := http.DefaultClient.Do(req) // No timeout! Blocks forever. ```

`http.DefaultClient` has zero timeout by default in Go. If the remote server: - Accepts the TCP connection but never sends a response - Establishes TLS but never completes the handshake - Uses TCP window size 0 (flow control stall)

...the goroutine blocks indefinitely. There is no context cancellation, no deadline, and no cleanup.

**3. No goroutine limit or backpressure:**

There is no limit on how many post-serve action gorout…