When you connect an AI agent to your core infrastructure, your security perimeter stops being defined by code. It is defined by text. In May 2026, OX Security exposed a critical flaw in Anthropic’s MCP SDKs affecting 200,000 servers. A month later, Unit 42 confirmed the first prompt injection attacks weaponized in the wild. This article breaks down exactly how both attacks work, why your existing logging misses them entirely, and the three infrastructure controls — a semantic firewall, zero standing privilege, and cryptographic context ledgering — that eliminate the core risk. No model-swapping required. No legacy rip-and-replace. Just circuit breakers built into your integration plumbing.