CVE-2026-79746

MCPHub prior to version 1.0.31 contains an incorrect authorization flaw (CWE-863) in how bearer API keys are validated for group routes. When a key with accessType 'servers' or 'custom' is used against a group route, isBearerKeyAllowedForRequest grants access if any single server in that group appears in the key's allowedServers list, and allowedServers is never re-checked once the group-level connection is authorized. An attacker holding a valid key scoped to just one server can therefore read from and interact with every other server sharing that group, including servers the key was never authorized for, driving the high confidentiality and integrity impact reflected in the CVSS 8.1 score. Only MCPHub deployments (self-hosted unified MCP server/API management hubs) that issue narrowly scoped bearer keys and use group routing are affected. There is no known exploitation, no public proof-of-concept, no CISA KEV listing, and EPSS puts 30-day exploitation probability at just 0.3%.

What to do: Upgrade MCPHub to version 1.0.31 or later, which restores per-server allowedServers checks on group routes. As an interim mitigation, audit bearer keys with accessType 'servers' or 'custom' and either avoid using narrowly scoped keys on group routes or scope them to every server in the groups they access, then review logs for group-route access beyond each key's intended scope.