Esbuild 0.18.3 is a patch release building upon the already impressive speed and efficiency of version 0.18.2, an extremely fast JavaScript and CSS bundler and minifier. While the core functionality remains the same, the key difference lies in bug fixes and minor improvements that enhance the stability and reliability of the tool. For developers, the upgrade from 0.18.2 to 0.18.3 promises a smoother experience with potentially fewer unexpected issues during the bundling process.
Both versions share identical dependency structures, relying on a suite of platform-specific packages (@esbuild/*) to deliver optimized performance across a wide range of operating systems and architectures, from Linux and Windows to macOS and Android. This comprehensive support ensures consistent behavior regardless of the development environment. The optionalDependencies field mirrors the dependencies, indicating that esbuild dynamically loads the appropriate platform-specific binary at runtime, only requiring the relevant package.
The fileCount and unpackedSize remain consistent between versions, however, the important variable that changed is the released date, upgrading from "2023-06-13T02:41:41.313Z" to "2023-06-15T12:22:23.909Z". Developers should consider upgrading to version 0.18.3 to take advantage of the latest enhancements and bug fixes, resulting in a more polished and dependable build process. Given the MIT license, developers have the freedom to use and modify the tool as needed. The project is actively maintained with the source code repository avaiable.
All the vulnerabilities related to the version 0.18.3 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.