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Malicious package

webpack-patchnpm

webpack-patch is a confirmed malicious npm package (MAL-2026-5581) that opens a backdoor for remote access (malicious versions 1.1.7, 1.1.8, 1.1.9…). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in webpack-patch (npm)

MAL-2026-5581
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall webpack-patch

What this malware does

Package impersonates the webpack ecosystem but is unrelated to webpack. When the exported middleware is invoked, index.js spawns a detached node lib/caller.js child. caller.js fetches https://jsonkeeper.com/b/XRGF3 via axios and passes the response's .cookie field to new Function.constructor('require', s)(require), executing attacker-controlled JavaScript with full Node privileges and a retry loop. The C2 URL and HTTP header name/value are stored as base64 strings under sham process.env keys (DEV_API_KEY base64-decodes to https://jsonkeeper.com/b/XRGF3); a sibling const.js variant points at https://jsonkeeper.com/b/4NAKK, providing pivot URLs if the primary paste is removed. jsonkeeper.com is an anonymous mutable paste host — whoever controls the paste controls arbitrary code execution on every consumer that loads webpack-patch and exercises its API. The package.json description is generic boilerplate copied from an unrelated security policy, and the main is a fake pino-style middleware whose only meaningful effect is launching the dropper.

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

4 flagged
1.1.71.1.81.1.91.2.0

Indicators of compromise (SHA-256)

d0f5ce3525e99528190ba5217a777184e302d46050fc23bef173de6fda240eba
c0fa02eb8a58fb15c7b71d6ab94306801f07b0a14ff28abb18e83a5063fce9ea
2e5981454fc68e5b3f5460c97c4a4fea3b98b208f795245e6d190a1f7dd56526
014c807f846f4ec5ff184415d090dcf6f972b6bfc40fba55592f1fe8067503cd
211fe03a2f3cc2baedeaf6395b413786d7ba17a709f0a7558a3f9777dcdc1ba3
630f6588b5bc3fb3ecd11fcaa4f852d272d9897c9de5fda06b4025fd6fd5a5fa
97032812fab9ccb8f1402ba416a2caf085a62c2da4fa7cd127f03cb43776473e

Detection & response playbook

Backdoor / remote access
  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for webpack-patch (4 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging webpack-patch across your stack and pipelines.

  2. If you installed it — respond

    webpack-patch 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.

  3. Did it already run?

    If webpack-patch 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.

  4. How O3 protects you

    O3 blocks webpack-patch 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. webpack-patch on npm has been identified as a malicious package (versions 1.1.7, 1.1.8, 1.1.9, 1.2.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-005546GHSA-3hxr-3hxr-pqq4IN-MAL-2026-009219IN-MAL-2026-009618IN-MAL-2026-009619RLMA-2026-05651

References

Credits

  • Amazon Inspector · finder
  • ReversingLabs · finder

Detect & block this

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

Explore

webpack-patch (npm) malicious package — MAL-2026-5581 | O3 Security