Affected: Homebrew: mcp-atlassian

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required). Version 0.17.0 fixes the issue.

Affected: sooperset mcp-atlassian

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required). Version 0.17.0 fixes the issue.

Affected: PyPI: mcp-atlassian

### Summary The `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required).

### Details The tool parameter is defined in `src/mcp_atlassian/servers/confluence.py:~1275` without any path restriction:

```python download_path: Annotated[ str, Field( description=( "Full path where the file should be saved. Can be absolute or relative. " "Examples: './downloads/report.pdf', '/tmp/image.png', 'C:\\\\temp\\\\file.docx'. " "Parent directory will be created if it doesn't exist." ) ), ],

The implementation at src/mcp_atlassian/confluence/attachments.py:183–200:

if not os.path.isabs(target_path): target_path = os.path.abspath(target_path) # normalizes path, no restriction

os.makedirs(os.path.dirname(target_path), exist_ok=True) # creates any directory with open(target_path, "wb") as f: # write…