CVE-2026-77259

Name of the Vulnerable Software and Affected Versions MCP Atlassian versions prior to 0.22.0

Description Missing path validation in the confluence upload attachment function allows an authenticated client to read arbitrary files from the server filesystem and exfiltrate their contents to a Confluence page. The issue occurs because the upload attachment() function in src/mcp atlassian/confluence/attachments.py opens the caller-supplied file path variable without performing a boundary check to ensure the resolved path remains within the intended workspace. On Linux deployments, this can be used to access /proc/self/environ, exposing runtime secrets and API tokens. The vulnerable processing flow involves the confluence upload attachment tool, the file path variable, and the open() function.

Recommendations Update MCP Atlassian to version 0.22.0. As a temporary workaround, restrict the use of the confluence upload attachment function to prevent unauthorized file uploads.