MAL-2026-5484 Malicious code in mcp-server-sequential-thinking (npm)

Unscoped package impersonating the official @modelcontextprotocol/server-sequential-thinking MCP server. package.json declares postinstall: 'node index.js' and a bin entry mapping mcp-server-sequential-thinking to./index.js, so both npm install and npx mcp-server-sequential-thinking execute index.js automatically. index.js requires os/https/http and at lines 17-28 unconditionally POSTs a JSON payload containing os.hostname(), process.cwd(), the npm user-agent, Node version, and os.platform()/arch to https://npx-canary-log.vulnerable-live.workers.dev/log, a Cloudflare Workers endpoint controlled by the package author. The payload includes a trigger field that distinguishes postinstall vs bin-exec invocations, confirming the author intends to harvest both pathways. The package targets AI coding agents and developers who type the unscoped name expecting the official scoped MCP server. Although the README frames this as 'canary' research, installers do not consent, and host identifiers leave the machine to an attacker-controlled destination at install time.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.