GHSA-2xj6-xx86-cwwc: Path Traversal
Summary A critical Confused Deputy (Arbitrary File Read & Exfiltration) vulnerability in the Atlassian MCP server (Python) allows an AI agent to exfiltrate sensitive host files and environment secrets. By providing absolute system paths to the attachments parameter of the updateissue tool, an agent can force the privileged MCP process to read and upload any file it has access to—including its own environment variables and host configuration—directly to a Jira ticket.
Details The vulnerability is located in the updateissue tool handler. The attachments parameter accepts a list of file paths that are passed directly to the Jira API's upload method without any sanitization or validation.
Specifically, the implementation fails to: 1. Restrict paths to a safe workspace: It accepts absolute paths starting with /. 2. Prevent directory traversal: It does not filter for ../ sequences. 3. Validate ownership: It allows the process to read system-level files (like /proc/self/environ) that the calling agent is normally forbidden from accessing due to sandbox restrictions.
Because the MCP server typically runs with higher privileges than the AI agent (holding the JIRAAPITOKEN and having wider filesystem access), it acts as a "Confused Deputy," performing exfiltration on behalf of a restricted agent.
PoC To reproduce the vulnerability in an environment where the agent is sandboxed (e.g., as a restricted Unix user) but the MCP server has host-level access:
1. Exfiltrate MCP Secrets: The agent calls the updateissue tool with the following payload: { "issuekey": "SECURITY-1", "attachments": ["/proc/self/environ"] } Result: The MCP server reads its own process environment—containing the JIRAAPITOKEN and other sensitive keys in plain text—and attaches it to the Jira issue.
2. Exfiltrate Host Configuration: The agent calls the tool to target global assistant settings: { "issuekey": "SECURITY-1", "attachments": ["/home/hermes/.hermes/config.yaml"] } Result: The host's global configuration file (containing tokens for GitLab, Slack, and other services) is successfully exfiltrated to the cloud.
Impact Critical Credential Theft: Immediate exposure of the JIRAAPITOKEN and any other secrets injected into the MCP server's environment. Arbitrary File Access: Total exfiltration of any data the host user running the MCP server can read (SSH keys, databases, local source code). Privilege Escalation & Lateral Movement: Attackers can move from a restricted AI sandbox to full host-system control by stealing tokens or configuration files.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/mcp-atlassianto a version that resolves this vulnerability.Fixed in 0.22.0 - Compensating control
In the Atlassian MCP server's update_issue attachment handler, restrict attachment paths to a designated safe workspace and reject absolute paths and ../ directory-traversal sequences before passing paths to the Jira upload method.
Event History
Frequently Asked Questions
Which deployments are exposed?
Deployments are exposed when the Python Atlassian MCP server allows an AI agent to invoke update_issue with attachments and the MCP process can read sensitive host files or environment data. The impact is greatest where the MCP process holds credentials such as JIRA_API_TOKEN or has broader filesystem access than the agent.
What does an attacker need to exploit this issue?
An attacker needs to cause an AI agent to provide attacker-chosen absolute paths or traversal paths in the update_issue attachments parameter. The MCP server then reads files accessible to its own process and uploads them to a Jira ticket.