The confluence_upload_attachment endpoint accepts an attacker-controlled file_path and does not enforce the path restriction that was added for earlier download vulnerabilities. An attacker can provide a crafted path that traverses outside the intended workspace, allowing the system to read any server‑side file that it has permission to read and to upload arbitrary files to Confluence. This can lead to confidential data disclosure and to the placement of malicious files that may be processed or served by Confluence, potentially compromising integrity and confidentiality of the system.

The vulnerability exists in the Sooperset MCP Atlassian server for Atlassian products (Confluence and Jira). All releases before version 0.22.0 are affected; the fix is delivered in 0.22.0.

The vulnerability carries a CVSS score of 8.6, indicating a high impact if exploited. EPSS data is not available, and it is not listed in CISA's KEV catalog. The likely attack vector requires the ability to send a request to the vulnerable endpoint with a crafted file_path, typically via an authenticated user action or API call. Due to the lack of a publicly known exploit, the probability of exploitation in the near term is uncertain, but the impact warrants prompt remediation.