log-format-threadnpm
Advisory published Updated
log-format-thread is a confirmed malicious npm package (MAL-2026-6848) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.0, 1.0.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in log-format-thread (npm)
What this malware does
Package advertises itself as a log formatter but exposes an undocumented threadContent option on createLogger() that is forwarded to a worker thread which compiles and executes it via new Function('require', payload)(require) (src/worker.js lines 5-7, triggered from src/index.js lines 148-151). The eval only runs against a payload the caller explicitly supplies, so installing or requiring the package does not by itself execute attacker-controlled code, and there are no install hooks, no remote fetches, no credential reads, and no outbound exfiltration. However, the feature is undocumented in the README, is shaped like a backdoor primitive rather than logging functionality, and the package also pulls in axios and request despite the README claiming 'Zero dependencies'. Consumers who pass user-controlled or otherwise untrusted data into threadContent would expose their application to arbitrary code execution. Routing to human review so a maintainer can decide whether to publish a public advisory about the undocumented eval surface and the dependency mismatch.
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
Credential / info stealerFind it
Search your lockfiles and build artifacts for log-format-thread (2 malicious versions).
If you installed it — respond
log-format-thread 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 log-format-thread 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 log-format-thread-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.