GHSA-wm45-qh3g-v83f: mcp-atlassian: Arbitrary server-side file read via attachment upload

A client that can invoke MCP tools can read arbitrary files from the server host and exfiltrate them as Atlassian attachments. The attachment-upload tools take a client-supplied file_path and open() it on the server’s filesystem.

The upload tools are meant to attach a file from the caller’s environment — the client supplies a path expecting it to refer to its own machine. Over a remote transport (HTTP/SSE) that path is instead resolved and read on the server, and the tool offers no way for the client to send file content in place of a server-side path. A remote client therefore reads the server’s files — and, in multi-tenant deployments, other tenants’ data — instead of its own. (In a local stdio deployment the server runs as the user, so the path refers to the user’s own files and reading any path is the intended behavior; the exposure is specific to remote/multi-user transports.)