{"version":"2.1.310","anchor":"mcp-allowdeny-matching-also-checks-a-second-expansion-of-th","canonical_anchor":"mcp-allowdeny-matching-also-checks-a-second-expansion-of-th","heading":"MCP server allow and deny lists check a second form of the server address","tier":"notice","area":"MCP","scope":"org","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.310\/e\/mcp-allowdeny-matching-also-checks-a-second-expansion-of-th","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.310","markdown":"### MCP server allow and deny lists check a second form of the server address\n\nFor some kinds of configuration, the allow and deny lists for MCP servers now match against a second worked-out form of the command or URL\n\n**Unclear.** It is not clear which kinds of server configuration get the second check or how the second form differs from the first.\n\n**What**\n\nOrganizations can control which MCP servers people may add with `allowedMcpServers` and `deniedMcpServers`. MCP servers are outside tools Claude Code connects to. To check a server against these lists, Claude Code works out the server's full command or web address. For certain kinds of server configuration, it now works this out a second time in a different way, and a match on either result counts.\n\n**Why**\n\nThis affects which MCP servers an organization's policy lets through or blocks, so it matters to anyone relying on these lists for security.\n\n- Area: MCP\n- Names: `allowedMcpServers`, `deniedMcpServers`\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: org\n- Heads-up: yes"}