CVE-2026-77257

# sooperset/mcp-atlassian: HTTP upload tools can attach arbitrary server-local files Date: 2026-05-05 Target: `sooperset/mcp-atlassian` Commit: `d8bc78698a63cb6b321c7ca796d6329d448f7f6d` ## Summary `mcp-atlassian` supports HTTP/SSE deployment for persistent, remote, and multi-user use. In that mode, write-capable Jira and Confluence attachment flows accept caller-controlled server-local file paths and read those paths without an upload-source allowlist or base directory restriction. An authenticated caller, or a prompt-injected agent with tool-call capability, can cause the MCP server process to read a local file it can access and attach that file into a Jira issue or Confluence page using configured Atlassian credentials. This is distinct from the prior download-path advisory: that issue was an arbitrary file write sink. This path is upload-source local file disclosure. ## Impact Impact is local file disclosure through an authenticated Atlassian attachment write. In Docker/Kubernetes deployments that mount `.env` or token material into the service, exposed files may include API tokens, OAuth credentials, service configuration, or other local secrets readable by the MCP process. The issue is bounded by tool access and Atlassian permissions: the attacker needs an MCP call path to a write tool and an issue/page where the attachment can be written. It is not direct RCE. Severity is Medium-to-High depending on deployment: - Medium for single-user/local stdio usage or tightly scoped tokens. - High where HTTP/streamable deployments are shared, write tools are exposed, and the server has access to secrets or broad filesystem mounts. ## Source Evidence HTTP/multi-user deployment is first-class: - `docs/http-transport.mdx:1-7` describes running as a persistent HTTP service for multi-user and remote deployment. - `docs/http-transport.mdx:10-13` lists SSE and streamable-http endpoints. - `docs/http-transport.mdx:88-90` says both HTTP transports support per-request