Threat database

CVE-2026-76844 is a high-severity path traversal vulnerability in webpack-dev-middleware. It arises from improper pathname validation when the configured publicPath lacks a trailing slash, allowing crafted requests to bypass traversal guards and access files outside the intended directory. This vulnerability affects versions starting from 5.3.4, 6.1.2, 7.1.0, and later up to 8.1.1. The issue is a partial regression of a previous vulnerability (CVE-2024-29180) and requires the middleware to be backed by a physical filesystem to be exploitable. No official patch or remediation guidance is currently provided.

webpack-dev-server allows users to use webpack with a development server that provides live reloading. Prior to version 5.2.1, webpack-dev-server users' source code may be stolen when you access a malicious web site with non-Chromium based browser. The `Origin` header is checked to prevent Cross-site WebSocket hijacking from happening, which was reported by CVE-2018-14732. But webpack-dev-server always allows IP address `Origin` headers. This allows websites that are served on IP addresses to connect WebSocket. An attacker can obtain source code via a method similar to that used to exploit CVE-2018-14732. Version 5.2.1 contains a patch for the issue.

webpack-dev-server allows users to use webpack with a development server that provides live reloading. Prior to version 5.2.1, webpack-dev-server users' source code may be stolen when they access a malicious web site. Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject a malicious script in their site and run the script. Note that the attacker has to know the port and the output entrypoint script path. Combined with prototype pollution, the attacker can get a reference to the webpack runtime variables. By using `Function::toString` against the values in `__webpack_modules__`, the attacker can get the source code. Version 5.2.1 contains a patch for the issue.