Accepts an attachments argument as a JSON array string or comma-separated string.
Converts it into attachment paths and passes them into the Jira update flow.
The project also documents non-stdio deployment modes:
sse
streamable-http
multi-user authentication
Docker and Kubernetes deployment
Therefore the upload path arguments should not be treated as if they always come from a single fully trusted local desktop user. In an HTTP or multi-user deployment, the caller and the server-local filesystem are separate security boundaries.
The core issue is that the MCP caller can choose a path, while the MCP server reads that path using the server process privileges and sends the bytes to a remote Jira or Confluence attachment endpoint.
Expected behavior:
Server-local file uploads should be denied by default in HTTP/SSE or multi-user deployments, or
Uploads should be constrained to an explicit allowlisted upload directory after realpath resolution, and
Dangerous path forms such as remote UNC paths and file:// URLs should be rejected before filesystem checks.
PoC
The following proof of concept uses a benign temporary file generated at runtime. It does not rely on prompt injection or any AI/LLM behavior. It uses a normal MCP client call against a test Confluence page controlled by the tester.
Prerequisites:
A test Confluence site.
A test page content ID where the tester is allowed to upload attachments.
A test Confluence API token or another supported authentication method.
The MCP client sends a normal confluence_upload_attachments tool call.
The MCP server reads the temporary file from its own filesystem.
The MCP server uploads that file as an attachment to the configured Confluence page.
The uploaded attachment appears on the test page.
Security significance:
The MCP caller did not need shell access to the server.
The MCP caller did not need direct filesystem access to the server.
The MCP caller only needed permission to invoke the upload tool.
The file read happened with the privileges of the MCP server process.
The same class of issue applies to Jira attachment upload flows that accept caller-controlled file path parameters.
Impact
This is a server-local file disclosure and exfiltration primitive through attachment upload tools.
Impacted users:
Users running mcp-atlassian with write/upload tools enabled.
Operators exposing mcp-atlassian through sse or streamable-http.
Multi-user deployments where MCP callers are not fully trusted with arbitrary read access to the MCP server filesystem.
Docker or Kubernetes deployments where the MCP process can read environment files, mounted secrets, service account tokens, application configuration, or shared volumes.
Potential attacker:
A malicious or compromised MCP client with permission to invoke attachment upload tools.
A malicious user in a multi-user MCP deployment.
An attacker who can supply or influence MCP tool arguments through an integrated workflow.
Potentially exposed data depends on the deployment, but can include files readable by the MCP server process, such as:
application configuration
deployment secrets
cloud or service credentials mounted into the runtime
CI/CD or automation tokens
other files available to the MCP server user
This issue does not require prior compromise of the internal network in deployments where the MCP service is intentionally exposed over HTTP/SSE to multiple users or external MCP clients. The attacker only needs the ability to invoke the upload tool. The server then reads the chosen path with its own process privileges and uploads it to Jira or Confluence.
If the intended security model is that every MCP caller is fully trusted with arbitrary read access to the server filesystem, that should be documented explicitly. Otherwise, server-local file path uploads should be opt-in and constrained to a configured upload root.
Suggested fixes:
Default-deny server-local path uploads in HTTP/SSE and multi-user deployments.
Add an explicit opt-in flag for server-local upload paths.
Require an allowlisted upload root and enforce it after realpath resolution.
Reject file:// URLs and remote UNC path forms before any filesystem operation.
Prefer client-provided file/resource blobs over server-local path strings for remote MCP deployments.