The issue is related to insufficient checking of incoming requests in WireMock, a tool for mocking HTTP services. This can allow a remote attacker to redirect POST requests to arbitrary services. The filtering of target addresses from the proxy mode did not work for Webhooks until WireMock Webhooks Extension 3.0.0-beta-15, making users potentially vulnerable regardless of the `limitProxyTargets` settings. Via the WireMock webhooks configuration, POST requests from a webhook might be forwarded to an arbitrary service reachable from WireMock’s instance.