CVE-2026-77253

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

Description Jira and Confluence attachment upload tools accept arbitrary local filesystem paths and send the selected bytes to Atlassian. In HTTP or multi-user deployments, a caller can cross the client-to-server filesystem boundary to disclose configuration, credentials, mounted secrets, or other files readable by the MCP process. This server-side arbitrary file read and exfiltration occurs because the implementation converts relative paths to absolute paths and opens them without validating if the path is safe or restricted to an allowed directory.

The issue affects the following components:

Recommendations Update MCP Atlassian to version 0.22.0. As a temporary mitigation, set READ ONLY MODE=true to block the affected write tools.