CVE-2026-73498 in mcp-atlassian
Summary
by MITRE • 08/12/2026
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, confluence_upload_attachment passes its client-supplied file_path directly to open(file_path, "rb") in src/mcp_atlassian/confluence/attachments.py through _upload_attachment_direct() without calling validate_safe_path. An authenticated MCP client can read any file accessible to the server process and exfiltrate it to Confluence as an attachment. If an AI agent can be induced to call the tool through untrusted content, the same flaw can disclose server environment variables such as CONFLUENCE_API_TOKEN and other credentials. This issue is fixed in version 0.22.0.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability exists within the Model Context Protocol (MCP) server implementation for Atlassian products, specifically affecting versions prior to 022.0. This flaw resides in the confluence_upload_attachment functionality where the system fails to properly validate file paths before processing them. The technical implementation directly passes client-supplied file_path parameters to Python's open() function without any sanitization or validation steps, creating a path traversal vulnerability that allows unauthorized file access.
The core technical flaw manifests in the src/mcp_atlassian/confluence/attachments.py module through the _upload_attachment_direct() function which bypasses the validate_safe_path validation mechanism entirely. This design oversight enables an authenticated attacker with MCP client privileges to specify arbitrary file paths that the server will attempt to open and read. The vulnerability operates at the file system level, allowing attackers to access any files that are readable by the server process running the MCP service.
The operational impact of this vulnerability extends beyond simple file reading capabilities. An authenticated MCP client can leverage this flaw to exfiltrate sensitive data from the server environment by uploading arbitrary files as Confluence attachments. This creates a significant data leakage risk where attackers can access not only regular files but potentially sensitive configuration data, credentials, and environment variables. The most concerning aspect occurs when AI agents are诱导 to invoke these tools through untrusted content, as this could lead to automatic credential disclosure without human intervention.
The vulnerability maps directly to CWE-22 Path Traversal and CWE-798 Use of Hard-coded Credentials in the Common Weakness Enumeration framework, representing a classic case of insufficient input validation combined with improper privilege management. From an ATT&CK perspective, this represents a technique for Credential Access (T1563) and Exfiltration (T1041) through legitimate system tools. The attack chain typically involves gaining authenticated access to the MCP service, crafting malicious file paths that traverse the filesystem, and then uploading the extracted content as Confluence attachments.
Mitigation strategies must focus on implementing proper input validation and path sanitization before any file operations occur. The fix implemented in version 0.22.0 requires calling validate_safe_path() function prior to processing file paths, ensuring that all user-supplied paths are properly validated against a whitelist of acceptable locations. Organizations should also implement principle of least privilege for the MCP server process, limiting its file system access to only necessary directories. Additionally, monitoring and logging of file access operations should be enabled to detect potential exploitation attempts. Network segmentation and access controls should restrict who can interact with the MCP service to prevent unauthorized access from external systems.