CISA warns of hackers now exploiting critical Node2Shell flaw

On Tuesday, the US Cybersecurity and Infrastructure Security Agency (CISA) confirmed that hackers have begun exploiting a critical Brotli vulnerability known as Node2Shell, Broccoli2Shell, and HTTP2Shell.

Tracked as CVE-2026-111497, this critical-severity flaw stems from an out-of-bounds write weakness in the Brotli decoder used to expand data compressed with Google's widely popular Brotli lossless compression algorithm.

Unprivileged attackers can use a maliciously crafted Brotli-compressed stream to trigger crashes or memory leaks and, in some cases, gain remote code execution on devices with vulnerable Brotli libraries or binaries.

The security issue was first identified in the Node.js JavaScript runtime environment, but it also affects HTTP servers and clients that rely on vulnerable Brotli implementations.