MetaMask SDK indirectly exposed via malicious debug@4.4.2 dependency

Who is affected?

This advisory only applies to developers who use MetaMask SDK in the browser and who, on Sept 8th 2025 between 13:00–15:30 UTC, performed one of the following actions and then deployed their application:

• Installed MetaMask SDK into a project with a lockfile for the first time
• Installed MetaMask SDK in a project without a lockfile
• Updated a lockfile to pull in debug@4.4.2 (e.g., via npm update or yarn upgrade)

What happened?

On Sept 8th, 2025 (13:00–15:30 UTC), a malicious version of the debug package (v4.4.2) was published to npm. The injected code attempts to interfere with dApp-to-wallet communication when executed in a browser context.

While MetaMask SDK itself was not directly impacted, projects installing the SDK during this window may have inadvertently pulled in the malicious version of debug.

Mitigation

• If your application was rebuilt and redeployed after Sept 8th, 2025, 15:30 UTC, the malicious version of debug should no longer be present. Please also verify that your package manager (npm, yarn, pnpm, etc.) is not caching debug@4.4.2.
• If you have not yet deployed since performing one of the actions above, delete your node_modules and reinstall dependencies before deploying.
• If your application was deployed during the attack window and has not been rebuilt since, perform a clean install of dependencies and redeploy to ensure the malicious package is removed.

Resources

GitHub Advisory for debug