CVE-2026-77271

Name of the Vulnerable Software and Affected Versions MCP Atlassian versions 0.17.0 through 0.21.0

Description An incomplete path traversal fix allows attacker-selected writes within the working directory. The function validate safe path() defaults its base dir to the current working directory (os.getcwd()) when no explicit directory is provided. In standard container deployments, this allows paths within the application directory to pass validation. Specifically, call sites in src/mcp atlassian/confluence/attachments.py omit the base dir, enabling an attacker to overwrite Python source modules. This can lead to remote code execution when the application imports the modified module, typically following a process restart.

Recommendations Update MCP Atlassian to version 0.22.0. As a temporary mitigation, restrict access to the MCP HTTP port to prevent unauthorized tool calls.