oh-langfusenpm
oh-langfuse is a confirmed malicious npm package (MAL-2026-4625) that steals credentials and exfiltrates sensitive data (malicious versions 0.1.21, 0.1.22, 0.1.28…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in oh-langfuse (npm)
What this malware does
The package configures Langfuse tracing for Claude Code, Codex, and OpenCode. When the operator runs the bundled CLI without explicitly overriding --langfuseBaseUrl, the setup writes LANGFUSE_BASEURL=http://120.46.221.227:3000 together with hardcoded public and secret Langfuse keys into ~/.claude/settings.json, ~/.codex/config.toml, OpenCode environment files, and shell shims (bin/cli.js lines 11-13 hardcode DEFAULT_LANGFUSE_BASE_URL = "http://120.46.221.227:3000", DEFAULT_LANGFUSE_PUBLIC_KEY = "pk-lf-da0c90a7-...", and DEFAULT_LANGFUSE_SECRET_KEY = "sk-lf-0269b85d-..."; scripts/langfuse-setup.mjs and scripts/opencode-langfuse-run.mjs reuse the same secret-key default). The installed Python hooks then ship every Claude/Codex turn — user prompts, assistant responses, tool inputs, and tool outputs (which routinely include file contents and any secrets observed in tool calls) — to that bare IPv4 endpoint. The destination is the publisher's own Langfuse instance, presented to the operator only as a numeric IP with no publisher-domain branding, served over cleartext HTTP, and pre-authenticated with credentials baked into the package. An additional fallback path in scripts/langfuse-setup.mjs downloads a hooks zip from https://gitcode.com/user-attachments/files/8187690/7a797a5314b9497cae7b055aa51be646.zip via PowerShell Invoke-WebRequest and installs it as the Claude Code Stop hook when both --pyPath is absent and the bundled langfuse_hook.py is missing — normally bypassed, but a brittle path to third-party-hosted code that Claude Code will execute. The trigger is the operator running the CLI with defaults (or --yes), not npm install; however, the documented invocation pattern of this package is to run that CLI, and the default behavior silently relays caller-supplied agent data (containing the operator's own code and secrets) to a publisher-controlled destination.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for oh-langfuse (18 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging oh-langfuse across your stack and pipelines.
If you installed it — respond
oh-langfuse is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If oh-langfuse 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 oh-langfuse 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 oh-langfuse-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.