Evidence record / claude-code
A dated record of one change, kept so the writing that cites it can be checked. Compiled from the sources listed below by the research run, not written for reading. The judgment lives in the signals and issues that cite it, below.
2026-09-21-claude-code-managed-mcp-and-policy-lists-go-fail-closed-allowedmcpservers-semantics-flip
2.1.259 (2026-09-02): an unparseable managed-settings file, drop-in, MDM plist or HKLM value was silently unenforced and now refuses to start; allowedMcpServers now governs only user-added servers, so a managed-mcp.json server the allowlist used to filter loads on upgrade; managedMcpServers ships HTTP and SSE servers to every user. 2.1.267: unreadable allowedHttpHookUrls, httpHookAllowedEnvVars and allowedChannelPlugins admit nothing rather than everything. 2.1.271: an unreadable managed-mcp.json keeps exclusive MCP control instead of being ignored; a cached org policy was reused after switching accounts. 2.1.273: allowManagedMcpServersOnly, deniedMcpServers and disableClaudeAiConnectors set via MDM or managed-settings.json were ignored when server-managed settings were also present.
Channel: tagged-release (2.1.259, 2.1.267 on stable; 2.1.271, 2.1.273 latest only). Half: both.
Operator consequence: If allowedMcpServers filtered managed-mcp.json, move exclusions to deniedMcpServers and check /mcp. Fleets layering MDM on server-managed settings had no working MCP deny list or connector kill switch before 2.1.273, and stable 2.1.267 still lacks that fix. A managed-settings file with a syntax error will now stop Claude Code from starting; fix it before rolling.
Receipt
Finding metadata
Run: 2026-09-21-weekly-digest-2026-08-20_2026-09-21-frontier-v0
Finding ID: 2026-09-21-claude-code-managed-mcp-and-policy-lists-go-fail-closed-allowedmcpservers-semantics-flip
Accepted signals
Profile citations
- Claude Code / claim / managed-lists-fail-closed
Source links
Primary links, including exact changelog lines when available.
Versioned source: run artifact