MalwarePublished 9 Sep 2026Updated 21 Sep 2026

@yongot/canary-mcp-isolation (npm) · Malicious Code

Affects @yongot/canary-mcp-isolationSource GCVE Database

Malicious package : remove @yongot/canary-mcp-isolation and rotate any secrets on hosts that installed it.

Data as of 24 Sep 2026, 04:34 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-16061

What to do

Remove @yongot/canary-mcp-isolation from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npm@yongot/canary-mcp-isolation	Affected =1.0.1 =1.0.0 =1.0.2	Fixed in–

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Description

The npm package @yongot/canary-mcp-isolation contains malicious code that exfiltrates host identifiers and cloud metadata information to a third-party webhook without user consent. This data exfiltration occurs automatically during package installation and import, sending information such as the installer's hostname, a persisted run marker, and cloud instance metadata reachability. The package claims to be a benign canary for authorized testing, but this does not mitigate the unauthorized data transmission.

Impact

Systems that install or import this package will leak host-specific identifiers and cloud metadata information to an external third-party endpoint. This unauthorized data exfiltration can lead to privacy violations and potential reconnaissance by malicious actors. There is no indication of further exploitation or active in-the-wild attacks at this time.

Defensive guidance

Users should avoid installing or importing the affected versions (=1.0.0, =1.0.1, =1.0.2) of the @yongot/canary-mcp-isolation package. Review your dependency tree for this package and remove it if found. Monitor for updates from the package maintainer or npm advisories for any official fixes or removals. Since this is not a cloud service, remediation depends on user action.

Summary

The @yongot/canary-mcp-isolation npm package versions 1.0.0, 1.0.1, and 1.0.2 include a postinstall script and runtime code that execute beacon.js. This script collects the installer's OS hostname, a persisted run marker from the temporary directory, and probes cloud instance metadata services at 169.254.169.254 and metadata.google.internal with the Metadata-Flavor: Google header. The collected data is sent via HTTP POST to a hardcoded webhook.site URL controlled by an unknown third party. This exfiltration happens automatically on npm install and on package import, without any user consent or configuration options to disable or redirect the data transmission. The package's self-description as a benign canary does not alter this behavior.

References

Community reviews

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What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Sep 2026, 04:34 UTC

Technical details

References

Community reviews