Esbuild version 0.17.0 represents a recent update to the extremely fast JavaScript and CSS bundler, succeeding version 0.16.17. While both versions share the same core functionality as a bundler and minifier, a key difference lies in the update of their dependencies. All platform-specific binaries within the dependencies and optionalDependencies fields, such as @esbuild/linux-x64, have been bumped from version 0.16.17 to 0.17.0. This indicates that the update likely includes performance improvements, bug fixes, or new features specific to the esbuild's native code handling for various operating systems and architectures, including Linux, Windows, macOS, Android, and others.
Developers should consider upgrading to version 0.17.0 to benefit from these platform-level enhancements, potentially leading to faster build times and improved stability across different environments. The consistent update across all platform-specific packages suggests a unified and coordinated release, ensuring a consistent experience regardless of the target platform. Furthermore, while the fileCount remains static at 7 between the versions, a small drop in unpackedSize from 127275 to 126932 potentially indicate a minor optimization in the build artifacts. The newer releaseDate also indicates more up-to-date bug fixes and features.
All the vulnerabilities related to the version 0.17.0 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.