MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, caller-supplied projects_filter and spaces_filter arguments can replace administrator-configured allowlists, and caller-provided project or space clauses can suppress the configured restriction. A caller can search projects or spaces outside the intended boundary when the configured Atlassian credentials can access them. The advisory traces the vulnerable input and processing flow through JIRA_PROJECTS_FILTER, CONFLUENCE_SPACES_FILTER, projects_filter, spaces_filter, SearchMixin.search_issues, and SearchMixin.search, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.