Esbuild is a blazing-fast JavaScript bundler and minifier, designed for optimal performance. Comparing versions 0.4.11 and 0.4.12, the difference lies primarily in the release date, with version 0.4.12 being released on June 9, 2020, shortly after 0.4.11 on June 8, 2020. Both versions share the same description, MIT license, repository details, file count (6), and unpacked size (20806).
While the core functionalities remain consistent between these specific versions, developers will want to consider upgrading to the newer 0.4.12 as it likely includes bug fixes or minor improvements implemented since the previous release. Though the data shared doesn't explicitly detail the changes, even small updates can contribute to increased stability and enhanced performance. Given esbuild's focus on speed, staying up-to-date ensures you're leveraging the most optimized version of the bundler. Furthermore, using the latest version allows you to take advantage of the newest features and improvements, improving the overall development workflow. For modern JavaScript projects prioritizing build times and efficiency, esbuild offers compelling solution, and keeping it updated, even with small increments, is the only way to ensure optimal usage.
All the vulnerabilities related to the version 0.4.12 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.