Esbuild versions 0.8.35 and 0.8.36 are both iterations of the extremely fast JavaScript bundler and minifier, designed to streamline web development workflows. While sharing the same core functionality, including the MIT license, repository details linking to the official GitHub, and identical unpacked sizes and file counts in their respective distribution packages, a key difference lies in their release dates. Version 0.8.35 was released on January 26, 2021, at 08:59:44.922Z, while version 0.8.36 followed shortly after on the same day at 11:17:13.370Z. This suggests that version 0.8.36 likely contains crucial bug fixes, performance enhancements, or minor feature additions implemented after the release of 0.8.35.
For developers seeking a reliable and efficient bundling solution, Esbuild delivers rapid build times, making it ideal for projects of any size. The choice between 0.8.35 and 0.8.36 hinges primarily on the potential need for the fixes or enhancements incorporated in the later release. Reviewing the changelog or release notes associated with version 0.8.36 is highly recommended to identify specific improvements and determine if they address any existing issues or enhance the developer experience. Ultimately, opting for the latest version, 0.8.36, generally ensures a more stable and optimized bundling process.
All the vulnerabilities related to the version 0.8.36 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.