Esbuild version 0.14.38 is a minor release of the extremely fast JavaScript and CSS bundler, building upon the solid foundation of version 0.14.37. Both versions share the same core description and functionality, focusing on speed and efficiency in bundling and minifying web assets.
The key difference lies in the updated dependencies. Both 0.14.37 and 0.14.38 feature identical sets of dependencies and optional dependencies covering a wide range of operating systems and architectures, including Linux, Windows, macOS (Darwin), FreeBSD, and others, supporting both 32-bit and 64-bit versions, along with ARM, ARM64, and other architectures. Crucially, version 0.14.38 updates these dependencies to their respective "0.14.38" versions. While the practical impact of this update might be minimal in terms of directly exposed features, it signifies important internal improvements, bug fixes, or optimizations within the platform-specific binaries. It's these underlying enhancements that provide the most value.
For developers, upgrading to 0.14.38 is recommended, especially if they've encountered any platform-specific issues or are simply seeking the most stable and up-to-date version. The upgrade will ensure you are running with the latest possible improvements. From a practical perspective, the upgrade will typically be seamless. The file count and unpacked size remain constant between the versions hinting at the change existing on the binary level related to each operating system for optimal performance.
All the vulnerabilities related to the version 0.14.38 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.