@agenticmail/mcp Missing Authentication for Critical Function
- Product
- npm/@agenticmail/mcp
- CVE
- CVE-2026-50287
- Affected
- @agenticmail/mcp < 0.9.27
- Fixed in
- 0.9.27
Last verified against sources: October 26, 2026
Am I affected?
npm/@agenticmail/mcp: affected @agenticmail/mcp < 0.9.27. Fixed in 0.9.27.
- Check your version: run
npm ls @agenticmail/mcp. Versions < 0.9.27 of @agenticmail/mcp are affected. [1]
What to do now
- Upgrade to the fixed version: run
npm install @agenticmail/mcp@0.9.27(first patched version 0.9.27). [1] - Require authentication for HTTP MCP mode. [1]
- Bind the MCP HTTP server to
127.0.0.1by default. [1] - Disable master-key tools when the transport is unauthenticated. [1]
General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.
What happened
@agenticmail/mcpexposes a Streamable HTTP transport when started with--httporMCP_HTTP=1. [1]- In that mode, the
/mcpendpoint accepts requests without any HTTP authentication layer. [1] - A remote client can initialize a session and call tools directly. [1]
- The MCP server also exposes tools documented as requiring
AGENTICMAIL_MASTER_KEY, and the server process forwards those calls using its own configured master key. [1]
Impact
- Any client that can reach the MCP HTTP port can invoke master-only operations without knowing the master key. [1]
- An unauthenticated network client can invoke master-key-only MCP tools through the server, including administrative and gateway actions. [1]
- The same path reaches higher-impact tools such as
setup_email_relay,setup_email_domain,delete_agent,cleanup_agents, andsend_test_email. [1]
What was done
- Packages: npm/@agenticmail/mcp affected < 0.9.27 patched 0.9.27 [1]
Sources
- GHSA-63gr-g7jc-v8rg — GitHub Advisory Database
Every statement above was checked against these sources before publishing. Spotted an error? Tell us and we will correct it with a dated note.
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[CVE-2026-50287] @agenticmail/mcp Missing Authentication for Critical Function
Product: npm/@agenticmail/mcp | Affected: @agenticmail/mcp < 0.9.27 | Fixed in: 0.9.27
Summary: `@agenticmail/mcp` exposes a Streamable HTTP transport when started with `--http` or `MCP_HTTP=1`.
Source & remediation on AgentArmorHQ: https://agentarmorhq.com/incidents/2026/06/cve-2026-50287-npm-agenticmail-mcpCorrections
Report an error or request a correction. We review requests within 5 business days and add a dated correction note.
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