Esbuild version 0.19.12 marks a subtle but significant evolution from its predecessor, 0.19.11, primarily concerning dependency management. A key distinction lies in the classification of platform-specific binaries. In version 0.19.11, these binaries (e.g., @esbuild/linux-x64, @esbuild/win32-arm64) were listed as both direct dependencies *and* optional dependencies. However, in version 0.19.12, they are exclusively designated as optional dependencies. This adjustment suggests a refinement in how esbuild handles platform-specific installations, likely aiming to streamline the core package size and improve installation robustness across diverse environments.
For developers, this change means that esbuild's core installation is leaner. The platform binaries will only be installed when they are needed. This difference could translate to faster initial installation times, particularly in situations where only a subset of target platforms are required. Esbuild remains a robust bundler and minifier renowned for its exceptional speed, supporting JavaScript and CSS. Both versions maintain the same core functionality and MIT license, ensuring continued accessibility and reliability. The core repository remains at GitHub, maintaining the provenance of the project. Upgrading from 0.19.11 to 0.19.12 should be seamless for most users, and is recommended, but developers should check if the new optional dependecies management breaks or change their build process.
All the vulnerabilities related to the version 0.19.12 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.