Junglewise Threat Intelligence

CVE-2026-77258: MCP Atlassian path traversal in attachment upload

CVE-2026-77258 · Severity: high · CVSS 7.7 · Published 2026-09-22

Technologies: Sooperset Mcp-Atlassian. Vendors: Sooperset.

Executive brief

MCP Atlassian is a server that extends Atlassian Confluence and Jira with AI-assisted capabilities. A vulnerability in versions prior to 0.22.0 allows authenticated users to upload arbitrary files from the server's filesystem as attachments, enabling disclosure of sensitive data like configuration files, credentials, and source code readable by the server process.

Technical details

The upload_attachment function in Confluence and Jira modules accepts caller-controlled file paths and opens them without path validation, allowing directory traversal via absolute paths or ../ sequences. An authenticated MCP caller can supply any file path readable by the server process, which is then uploaded and disclosed as an attachment. The fix validates all file paths against the workspace using a validate_safe_path function, confining uploads to the working directory.

Affected products

  • sooperset mcp-atlassian before 0.22.0

Timeline

  • 2026-09-22: disclosed
  • 2026-07-10: patched

References

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