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Malicious package

eslint-helpernpm

Advisory published Updated

eslint-helper is a confirmed malicious npm package (MAL-2026-6187) that steals credentials and exfiltrates sensitive data (malicious versions 4.0.1, 4.0.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in eslint-helper (npm)

MAL-2026-6187
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall eslint-helper

What this malware does

Package masquerades as an ESLint utility but contains no lint-related code. The exported from_str() recursively walks process.cwd() searching for secret-bearing files (.env, config.toml, Config.toml, config.json, env, id.json) and POSTs each file's contents to a hardcoded, base64-obfuscated endpoint at https://vercel-backend-five-vert.vercel.app/api/v1. A helper _gsh() additionally reads ~/.bash_history, ~/.zsh_history, fish history, and PowerShell PSReadLine ConsoleHost_history.txt, and shells out via execSync("bash -c history") and execSync("zsh -c 'fc -l -1000'") to dump in-memory shell history, then ships each to the same endpoint. All sensitive strings (target filenames, exfil URL, HTTP headers, USER env var name) are base64-obfuscated and decoded at module load via a decodeStr helper, indicating intentional evasion. Any project that requires this package and invokes from_str (or runs the shipped test.js) will leak credentials and shell history to the attacker.

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

2 flagged
4.0.14.0.2

Indicators of compromise (SHA-256)

287d2ce5e8564f37ce829dd1a28c92c7f484637512ac3174628a89181fb6e5b1
5802f88a31cfb1c54196395aa04377de1c98657cdd78f59e4a595f2913239301
a12235e67c9b0720356aa892ed51f2256ef30f7eb599f45b8d50eb9191aedd36

Detection & response playbook

Credential / info stealer
  1. Find it

    Search your lockfiles and build artifacts for eslint-helper (2 malicious versions).

  2. If you installed it — respond

    eslint-helper 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.

  3. Did it already run?

    If eslint-helper 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

No. eslint-helper on npm has been identified as a malicious package (versions 4.0.1, 4.0.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-007041IN-MAL-2026-007044GHSA-m23v-7h8v-6mp4

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks eslint-helper-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Explore

eslint-helper (npm) malicious package — MAL-2026-6187 | O3 Security