An MCP agent calls read_file, works. Calls write_file, gets a 403 with scope=”files:write”, re-authorizes for files:write, works. Calls read_file again, 403, scope=”files:read”. It re-authorizes, and now write_file fails. Both sides are behaving as specified: the MCP authorization specification permits…
First seen on securityboulevard.com
Jump to article: securityboulevard.com/2026/09/fixing-insufficient_scope-403s-in-mcp-step-up-authorization/
