The vulnerability in sooperset mcp-atlassian (prior to version 0.22.0) arises from improper limitation of a pathname to a restricted directory (CWE-22). The Jira and Confluence attachment upload tools treat caller-controlled file_path values as trusted local paths without sufficient validation. This allows an attacker with upload access to open and disclose any file readable by the server process by specifying arbitrary file paths. The vulnerable code paths include confluence_upload_attachment, jira_upload_attachment, file_path, and the use of open(file_path, "rb"). The issue is resolved in version 0.22.0.

An attacker with upload access to the MCP Atlassian server can read arbitrary files on the server that are accessible by the server process. This leads to a confidentiality breach (high impact on confidentiality) but does not affect integrity or availability. The CVSS 3.1 base score is 6.5 (medium severity) reflecting network attack vector, low attack complexity, required privileges, no user interaction, and high confidentiality impact.

Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where this path traversal vulnerability is fixed. No other mitigation is indicated or required according to the advisory.