Esbuild version 0.19.4 represents a minor version update over the previous stable release, 0.19.3, in the popular JavaScript and CSS bundler and minifier. Both versions maintain the same core functionality, providing developers with an extremely fast tool for optimizing web assets. The primary differences lie in the version bumps of the architecture-specific packages, like @esbuild/linux-x64, @esbuild/darwin-arm64, and others, reflecting potential bug fixes, performance enhancements, or compatibility updates within those specific platform binaries.
For developers, upgrading from 0.19.3 to 0.19.4 should be a relatively straightforward process. Given the identical structure of dependencies and optionalDependencies, existing project configurations should remain compatible. The identical description, license, and repository information highlight the stability and continued maintenance of the project.
While the core engine's API remains consistent, the updated platform-specific packages suggest that the developers behind esbuild are actively ensuring cross-platform compatibility and optimizing performance for various operating systems and architectures. This focus on platform support makes esbuild a reliable choice for projects targeting diverse deployment environments. The updated releaseDate also confirms that the library is actively maintained which is a key factor for any developer that wants to adopt this library.
All the vulnerabilities related to the version 0.19.4 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.