If this package is installed
Remove it, treat the machine (or CI runner) as compromised, and rotate every secret, token and key it could access — from a different, clean machine.
Details
Source: amazon-inspector (18f32429d1bfdc9438f2f03f531e5c2fef53e0e69104e3124499cf6f42ce52a1)
package.json declares a postinstall lifecycle script that runs curl against https://webhook.site/<id> with the installer's hostname appended as a query parameter, transmitting the host identifier to a third-party request-inspection collector on every npm install. The package name @medisend/core with version 0.0.1-security-research and a description referencing a dependency-confusion test targets internal builds that expect a private @medisend/core package; when such a build resolves this public package instead, the postinstall runs automatically and leaks the installer's hostname off-host. The self-labelled 'security research' framing does not change the effect: any installer that resolves this package executes an unconsented host-identifier beacon to a destination controlled by whoever provisioned the webhook.site URL.
Source: ghsa-malware (4a8c872aa8b3ed68e9054cddab1f0652b633fb297b6580ba2eee5ec9376ed409)
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.