Esbuild version 0.8.47 refines the popular JavaScript bundler and minifier, building upon the foundations of version 0.8.46. Both versions champion speed and efficiency, offering developers a significantly faster alternative to traditional bundling tools. They share the same MIT license, ensuring broad usability, and are maintained within the active GitHub repository.
A key difference lies in the release date, with version 0.8.47 arriving on February 18, 2021, four days after version 0.8.46's release on February 14, 2021. The newer version also has a slightly smaller unpacked size (71318 bytes compared to 71765 bytes), suggesting potential optimizations and refinements to the codebase and assets. While both packages contain the same number of files (6), the size difference highlights underlying improvements.
For developers, these versions of Esbuild continue to provide a compelling solution for bundling and minifying JavaScript. The speed benefits translate to faster build times and improved development workflows. The active repository implies the project is well maintained and responsive community and the difference in size from the previous version denotes that there are improvements with each new version of the library. The choice depends on each developer's priorities, however, always is recommended to update to the latest version of a library.
All the vulnerabilities related to the version 0.8.47 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.