# MAL-2026-17763: Malicious code in @coopeuch/core (npm)


- **Type:** Malicious package
- **Package:** `@coopeuch/core` (npm)
- **Published:** 11 Oct 2026
- **Also known as:** GHSA-8jgp-jmwc-7fxg

## What is MAL-2026-17763?

MAL-2026-17763 is a malicious package in @coopeuch/core, published on 11 Oct 2026. 

### Official description

On npm install, postinstall.js automatically executes and collects a detailed host and environment report — hostname, username, uid/gid, home directory, platform/arch/release, CPU and memory, DNS servers, non-internal network interfaces (name, address, MAC, CIDR), reverse-DNS internal FQDN, container/orchestrator detection, selected npm_* environment variables including scoped registry configuration, CI markers, current working directory, and the parent consuming project's package.json name, version, and declared dependency range. The JSON report is POSTed to https://collector.oob.s4yhii.com/_npm-poc/beacon and a DNS lookup is issued against a subdomain of oob.s4yhii.com as a secondary out-of-band channel. The package is published publicly as @coopeuch/core at version 1.999.999, a version-number shape designed to win resolution against an internal @coopeuch scope — the canonical dependency-confusion attack shape, confirmed by the beacon specifically reporting the consumer's scoped registry env var and internal manifest coordinates. The installer did not consent to disclosing host identity, internal network topology, or the identity of their private project to a third-party host; a self-described proof-of-concept or coordinated-disclosure framing in the package does not change that the code runs unprompted on install and ships installer-identifying data off-host.

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.

## What should I do about MAL-2026-17763?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-17763 is a malicious package: @coopeuch/core (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-17763/ (Markdown: https://insights.sbomify.com/MAL-2026-17763/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-17763

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-17763/
Summaries are generated and may contain mistakes; the official description above is the record.