Esbuild is a blazing fast JavaScript bundler and minifier, and versions 0.0.12 and 0.0.13 showcase its continuous development. A key difference between the two versions lies in their distribution structure. Version 0.0.12 relies on platform-specific optional and regular dependencies (esbuild-linux-64, esbuild-darwin-64, esbuild-windows-64), essentially pulling in the correct binary based on the user's operating system. This approach, while functional, resulted in a smaller initial package size (327 bytes unpacked) but required additional downloads during installation. In constrast, version 0.0.13 delivers a single, self-contained tarball (1783 unpacked size).
For developers, this is a significant change. Version 0.0.13 simplifies the installation process, eliminating the need for conditional dependency resolution and reducing potential platform-specific issues. The older version's dependency on platform-specific packages made the install process more complex since the package manager needed to download the right pacakge, while the later version simplifies this at the cost of an increased initial size.
Both versions share the same MIT license and are hosted on GitHub, ensuring transparency and open-source accessibility. This means developers can freely use, modify, and distribute esbuild according to the terms of the license. Choosing between the two depends on your priorities: smaller initial download size and slightly more complex install or a more convenient single-package installation
The release dates are close together, potentially meaning that there was a bug fixing in version 0.0.13.
All the vulnerabilities related to the version 0.0.13 of the package
esbuild enables any website to send any requests to the development server and read the response
esbuild allows any websites to send any request to the development server and read the response due to default CORS settings.
esbuild sets Access-Control-Allow-Origin: * header to all requests, including the SSE connection, which allows any websites to send any request to the development server and read the response.
https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L121 https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L363
Attack scenario:
http://malicious.example.com).fetch('http://127.0.0.1:8000/main.js') request by JS in that malicious web page. This request is normally blocked by same-origin policy, but that's not the case for the reasons above.http://127.0.0.1:8000/main.js.In this scenario, I assumed that the attacker knows the URL of the bundle output file name. But the attacker can also get that information by
/index.html: normally you have a script tag here/assets: it's common to have a assets directory when you have JS files and CSS files in a different directory and the directory listing feature tells the attacker the list of files/esbuild SSE endpoint: the SSE endpoint sends the URL path of the changed files when the file is changed (new EventSource('/esbuild').addEventListener('change', e => console.log(e.type, e.data)))The scenario above fetches the compiled content, but if the victim has the source map option enabled, the attacker can also get the non-compiled content by fetching the source map file.
npm inpm run watchfetch('http://127.0.0.1:8000/app.js').then(r => r.text()).then(content => console.log(content)) in a different website's dev tools.Users using the serve feature may get the source code stolen by malicious websites.