Which versions of cspell-esm are malicious?

The following npm versions of cspell-esm are flagged malicious: 99.9.1. Treat any of these as compromised.

How do I remediate cspell-esm if I installed it?

cspell-esm is a typosquat — you almost certainly intended a legitimately-named package. Remove cspell-esm, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

I already installed cspell-esm — how do I know if it already compromised me?

If cspell-esm 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.

Is cspell-esm part of a known attack campaign?

Yes — cspell-esm is associated with the IN-MAL-2026-017683 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find cspell-esm across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for cspell-esm (version 99.9.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging cspell-esm across your stack and pipelines.

Malicious package

cspell-esmnpm

cspell-esm is a confirmed malicious npm package (MAL-2026-13977) that typosquats a legitimate package to trick installs (malicious version 99.9.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in cspell-esm (npm)

MAL-2026-13977

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall cspell-esm

What this malware does

Package name resembles the widely-used 'cspell' library but its main entry (index.js) exports an empty object and provides no functionality. Its package.json pins its sole dependency 'ltidisafe' to a raw HTTPS URL on a Google Cloud Storage bucket (https://ltidi.storage.googleapis.com/depenconf/ltidisafe-3.6.7.tgz) rather than a registry-published, version-pinned artifact. On npm install, npm fetches this tarball from the author-controlled bucket and installs it into the dependency tree, executing any of its lifecycle scripts and main-module code on the installer's machine. The combination of a lookalike name, an empty implementation, and an off-registry dependency source is the dropper-lure shape: the lure package itself is inert, and installer-side code execution is delivered through the smuggled dependency.

Malicious versions

1 flagged

99.9.1

Indicators of compromise (SHA-256)

6e857800f57969e257ed22cd056f2e4a4395de09ac9b69becd0c7c2b931314ab

Detection & response playbook

Typosquat

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for cspell-esm (version 99.9.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging cspell-esm across your stack and pipelines.
If you installed it — respond
cspell-esm is a typosquat — you almost certainly intended a legitimately-named package. Remove cspell-esm, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If cspell-esm 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 cspell-esm 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

No. cspell-esm on npm has been identified as a malicious package (version 99.9.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-017683

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks cspell-esm-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.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database