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fkie_cve-2026-77246

2026-10-02T15:29:45.408143+00:00

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.

GHSA-wv8v-v4c5-v75j — MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

2026-10-02T15:29:45.408235+00:00

Affected: PyPI: mcp-atlassian

### Summary

The `mcp-atlassian` server exposes an MCP tool (`confluence_upload_attachment` and the Jira attachment variant) that accepts an arbitrary server-side file path and opens it for upload without any path validation. When the server is deployed in HTTP transport mode (`streamable-http` or `sse`), a remote, unauthenticated attacker can supply attacker-controlled Atlassian service headers (`X-Atlassian-Confluence-Url` / `X-Atlassian-Confluence-Personal-Token`) to redirect the upload to an attacker-controlled endpoint, then pass an arbitrary `file_path` (e.g. `/etc/passwd`, `~/.env`, SSH private keys, cloud credentials) to exfiltrate any file readable by the server process. No prior account, session token, or `Authorization` header is required. The vulnerability was confirmed through both static code analysis (Phase 1) and a live Docker-based proof-of-concept (Phase 2).

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### Details

**Data flow (source → sink)**

| Step | Location | Role | |------|----------|------| | 1 | `src/mcp_atlassian/servers/main.py:498-504` | Middleware extracts `X-Atlassian-Confluence-Url` and `X-Atlassian-Confluence-Personal-Token` from incoming HTTP request headers. | | 2 | `src/mcp_atlassian/servers/main.py:584-595` | When no `Authorization` header is present but service headers are, `user_atlassian_auth_type` is set to `"pat"`, effectively bypassing authentication requirements. | | 3 | `src/mcp_atlassian/utils/urls.py:97-104` | `validate_url_for_ssrf` blocks only `localhost`, RFC 191…

PYSEC-2026-4104 — MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

2026-10-02T15:29:45.408434+00:00

Affected: PyPI: mcp-atlassian

### Summary

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### Details

**Data flow (source → sink)**