Affected: Homebrew: mcp-atlassian

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Affected: sooperset mcp-atlassian

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Affected: PyPI: mcp-atlassian

### Summary An unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169.254.169.254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results.

### Details The server supports a multi-tenant HTTP authentication mode where clients supply per-request Jira/Confluence URLs via custom headers. The middleware (`src/mcp_atlassian/servers/main.py:436–448`) extracts `X-Atlassian-Jira-Url` from the request and stores it in request state with no validation. The dependency provider (`src/mcp_atlassian/servers/dependencies.py:189–217`) then uses this value directly as the `url=` parameter when constructing a `JiraConfig` and `JiraFetcher`. The first method call on the fetcher (`get_current_user_account_id()`) immediately issues a `GET` request to `{header_url}/rest/api/2/myself` — an outbound SSRF call to the attacker-controlled URL.

No comparison is made against the server-configured `JIRA_URL` environment variable. No private IP…