Esbuild versions 0.5.1 and 0.5.2 showcase incremental improvements to this exceptionally fast JavaScript bundler and minifier. Both versions, licensed under MIT, maintain the core functionality that developers appreciate: rapid build times, efficient minification, and a simple API. The essential metadata, including description, repository details, and distribution specifics like file count and unpacked size, are identical between the two releases.
The primary distinction lies in their release dates. Version 0.5.2 was published on June 12, 2020, shortly after version 0.5.1's release on June 11, 2020. This suggests that the newer version likely addresses minor bugs, performance tweaks, or perhaps includes very small feature enhancements discovered immediately following the prior release.
For developers considering esbuild, either version provides a powerful tool. The minimal difference indicates that opting for 0.5.2 is generally recommended to benefit from any immediate post-release refinements. While the core functionality remains consistent, staying current ensures you leverage the most optimized and stable iteration. Esbuild shines in scenarios demanding swift compilation and minimal bundle sizes, making it ideal for large projects, continuous integration/continuous deployment pipelines, and optimizing web application loading speeds.
All the vulnerabilities related to the version 0.5.2 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.