cloudflareAug 14, 2026

How Cloudflare detects MCP traffic and helps secure it (opens in new tab)

AI agents change the risk model for resource permissions because they make nondeterministic decisions and can repeat actions at machine speed. A mistaken judgment that a human might quickly catch can become thousands of harmful operations before anyone notices. Cloudflare’s new Cloudflare One capabilities aim to detect MCP traffic, identify its users and servers, and enforce approved routes through MCP Server Portals. ## Why AI Agents Require New Controls - Traditional permissions assumed users would apply judgment and act at a limited human pace. - AI agents can invoke tools repeatedly and indefinitely. - A single incorrect decision can rapidly propagate across databases, SaaS systems, or infrastructure. - MCP makes it easy to connect clients such as Claude Code, Codex, Cursor, OpenCode, and VS Code to approved or unapproved tools. - Direct MCP traffic can resemble ordinary HTTPS because MCP does not require a standard hostname or `/mcp` path. ## Anatomy of an MCP Tool Call An MCP request appears differently at three points: - **Client:** The agent decides to invoke a tool and supplies arguments. - **Network:** The request is transmitted as an HTTP transaction containing JSON-RPC. - **Server:** The server authenticates, validates, and dispatches the request to a tool handler. Useful protocol signals include: - Destination hostname and path - Authorization credentials - `MCP-Protocol-Version` - `Mcp-Method` - `Mcp-Name` - JSON-RPC request `id` - Tool arguments in `params` The tool name indicates the intended operation, while the arguments may contain sensitive data such as source code, customer information, search queries, or infrastructure-changing instructions. Responses can also contain sensitive results, making both request prevention and response inspection valuable. ## Controls Inside the MCP Client Client hooks can intervene after the model selects a tool but before the request is serialized. - Enforce server allowlists - Require confirmation for sensitive operations - Remove sensitive data from arguments - Support local `stdio` MCP servers that never generate network traffic The main limitation is operational: organizations must implement controls across every client employees use. Client telemetry also cannot provide a complete inventory unless the organization manages all relevant clients and devices. ## Controls at the Network Boundary A secure web gateway with TLS decryption can inspect remote MCP traffic independently of the client. - Associate requests with users and devices - Inspect destinations and MCP protocol headers - Detect direct connections outside approved MCP Portals - Block unauthorized traffic before it reaches the server - Use data loss prevention scanning to inspect JSON-RPC methods and arguments Network controls provide the broadest visibility into remote MCP usage, but they cannot see local `stdio` calls or traffic that bypasses managed network paths. ## Controls at the MCP Server The server has the deepest execution context because it knows the authenticated caller, parsed message, resolved tool, and validated arguments. Server-side middleware can: - Authorize users for specific tools - Apply rate limits - Inspect arguments - Log outcomes - Block requests before tool execution Cloudflare’s WriteGuard applies this approach to internal MCP servers by assigning tools risk tiers and enabled or disabled states. It can allow reads, attach attribution and audit events to approved writes, or block critical actions before their handlers run. Because enforcement occurs on the server, users cannot bypass it by changing clients or disabling local hooks. ## Layered MCP Security Each control point has a different strength: - **Client controls:** Earliest intervention and support for local MCP, but limited coverage. - **Network controls:** Broadest visibility into remote traffic and unmanaged MCP connections. - **Server controls:** Richest context and final prevention point before execution. A layered strategy can protect sensitive data before it leaves a device, identify shadow MCP usage, require trusted Portal-based access, and prevent unauthorized tools from executing.

secure-web-gatewayai-agentmodel-context-protocolaccess-control+4

cloudflareFeb 23, 2026

Cloudflare One is the first SASE offering modern post-quantum encryption across the full platform (opens in new tab)

Cloudflare says Cloudflare One is now the first SASE platform to provide standards-compliant post-quantum hybrid ML-KEM encryption across Secure Web Gateway, Zero Trust, and WAN connectivity. The update extends protection to Cloudflare IPsec and Cloudflare One Appliance, addressing both current “harvest now, decrypt later” attacks and future quantum threats. The appliance support is generally available in version 2026.2.0, while Cloudflare IPsec is in closed beta. ## Post-Quantum Cryptography Is an Immediate Concern - NIST has set 2030 as the target for phasing out RSA and elliptic-curve cryptography in favor of post-quantum algorithms. - Cryptographic migrations can take decades, as demonstrated by vulnerabilities involving deprecated algorithms such as MD5. - Organizations face “harvest now, decrypt later” attacks, in which encrypted traffic is collected today for future decryption. - Cloudflare argues that built-in crypto agility makes it easier for enterprises to upgrade algorithms without redesigning remote-access and WAN infrastructure. ## Two Required Cryptographic Migrations - **Key establishment:** ML-KEM is becoming the standard post-quantum mechanism for establishing shared encryption keys. - Cloudflare uses hybrid ML-KEM, combining ML-KEM with classical ECDHE. - This approach protects against harvested traffic, requires no specialized hardware like quantum key distribution, and has limited performance impact. - More than 60% of human-generated TLS traffic reaching Cloudflare is already protected by hybrid ML-KEM. - **Digital signatures:** Post-quantum signatures protect against server impersonation but are larger than current ECC signatures. - Their migration is considered less urgent because they primarily defend against active quantum adversaries, which do not yet exist. - Cloudflare’s current IPsec work therefore focuses on post-quantum key establishment rather than signatures. ## Post-Quantum Protection for Cloudflare IPsec - Cloudflare upgraded its IPsec products to support hybrid ML-KEM within IKEv2. - Cloudflare IPsec creates encrypted tunnels from customer networks to Cloudflare’s global network. - IP Anycast routes tunnels to the nearest data center and automatically redirects traffic if a location becomes unavailable. - The service supports site-to-site WAN connectivity as well as outbound Internet connections. - Cloudflare One Appliance, which establishes Cloudflare IPsec connections, supports the upgrade starting with version 2026.2.0. - The Cloudflare IPsec upgrade remains in closed beta. ## Limitations of Earlier IPsec Approaches - IPsec has historically evolved differently from TLS because it is commonly used between devices from the same vendor, making interoperability less central. - RFC 8784 proposed combining long-lived pre-shared keys with Diffie-Hellman exchange. - While this can help protect against harvest-now-decrypt-later attacks, it does not provide forward secrecy against quantum attackers. - Quantum key distribution is also impractical for many enterprise environments because it requires specialized physical connectivity. Cloudflare’s recommendation is to begin post-quantum migration now, starting with hybrid ML-KEM for key establishment across Internet access, Zero Trust, and WAN connections.

secure-web-gatewayzero-trustnetwork-securitypost-quantum-cryptography+4