Which versions of midpatch are malicious?

The following npm versions of midpatch are flagged malicious: 1.1.9. Treat any of these as compromised.

How do I remediate midpatch if I installed it?

midpatch establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed midpatch — how do I know if it already compromised me?

If midpatch 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 midpatch part of a known attack campaign?

Yes — midpatch is associated with the IN-MAL-2026-004364 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 midpatch across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for midpatch (version 1.1.9).

Malicious package

midpatchnpm

Advisory published May 23, 2026Updated May 26, 2026

midpatch is a confirmed malicious npm package (MAL-2026-4611) that opens a backdoor for remote access (malicious version 1.1.9). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in midpatch (npm)

MAL-2026-4611

Immediate action

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

npm uninstall midpatch

What this malware does

The package advertises a logger middleware (keywords fast/logger/stream/json, exports module.exports.pino = middleware, file.js wraps a ./pino module) so consumers will install and mount it as Express middleware. On first invocation, index.js spawns a detached, stdio-ignored child process running node lib/caller.js, which fetches JavaScript from https://jsonkeeper.com/b/XRGF3 (a public, attacker-mutable paste host) and evaluates the response's cookie field via new Function.constructor('require', s)(require), granting the remote payload full Node require access. The C2 URLs are base64-obfuscated inside fake process.env defaults (DEV_API_KEY: "aHR0cHM6Ly9qc29ua2VlcGVyLmNvbS9iL1hSR0Yz" and a second paste ID 4NAKK in lib/const.js) to evade casual review and string scanners. The combination of pino-shaped lure + detached/hidden child + remote-fetched eval from a mutable paste host + base64-hidden endpoints is unambiguous supply-chain RCE — any consumer that mounts the middleware executes attacker-controlled code.

Malicious versions

1 flagged

1.1.9

Indicators of compromise (SHA-256)

fe668e556f4b46fce125c318ebc3bea93185c78ec36c19f8991bbcb36172a62b

Detection & response playbook

Backdoor / remote access

Find it
Search your lockfiles and build artifacts for midpatch (version 1.1.9).
If you installed it — respond
midpatch establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If midpatch 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. midpatch on npm has been identified as a malicious package (version 1.1.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-004364

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks midpatch-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database