Hackers Exploit Metro4Shell RCE Flaw in React Native CLI npm Package

Threat actors have been observed exploiting a critical security flaw impacting the Metro Development Server in the popular “@react-native-community/cli” npm package.

Cybersecurity company VulnCheck said it first observed exploitation of CVE-2025-11953 (aka Metro4Shell) on December 21, 2025. With a CVSS score of 9.8, the vulnerability allows remote unauthenticated attackers to execute arbitrary operating system commands on the underlying host. Details of the flaw were first documented by JFrog in November 2025.

Despite more than a month after initial exploitation in the wild, the “activity has yet to see broad public acknowledgment,” it added.

In the attack detected against its honeypot network, the threat actors have weaponized the flaw to deliver a Base64-encoded PowerShell script that, once parsed, is configured to perform a series of actions, including Microsoft Defender Antivirus exclusions for the current working directory and the temporary folder (“C:\Users\<Username>\AppData\Local\Temp”).