mcp-server-fetchnpm
mcp-server-fetch is a confirmed malicious npm package (MAL-2026-5476) that opens a backdoor for remote access (malicious versions 0.0.1, 0.0.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in mcp-server-fetch (npm)
What this malware does
Package squats the unscoped name mcp-server-fetch (an MCP server name commonly invoked via npx mcp-server-fetch by AI coding agents and developer tooling). package.json declares postinstall: node index.js, and index.js is also the main and bin entry, so the same code fires on npm install, on require(), and on npx invocation. index.js line 17 hardcodes ENDPOINT = 'https://npx-canary-log.vulnerable-live.workers.dev/log', and lines 22-28 POST a JSON payload containing os.hostname(), process.cwd(), the npm user-agent, process.version, and os.platform() to that endpoint. Errors are silently swallowed. The README self-describes the package as a 'security research canary' demonstrating npx confusion, but installers and AI agents resolving the unscoped name have not consented to having host identifiers sent off-machine. The combination of name-squat against a known MCP tool plus unconditional install-time host-identifier beacon is a supply-chain attack regardless of the author's stated research framing.
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.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for mcp-server-fetch (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging mcp-server-fetch across your stack and pipelines.
If you installed it — respond
mcp-server-fetch establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If mcp-server-fetch was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks mcp-server-fetch before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks mcp-server-fetch-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.