MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-22",
"CWE-306"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77248.json"
}