Esbuild version 0.6.7 marks a subtle yet potentially relevant update to the blazing-fast JavaScript bundler and minifier, building upon the solid foundation of version 0.6.6. Both versions share the same core identity: a tool designed for exceptional speed in bundling and minifying JavaScript code, licensed under the MIT license, and maintained within the active GitHub repository under evanw.
The key difference lies primarily in the "unpackedSize" attribute within the "dist" object. Version 0.6.7 exhibits a slightly larger unpacked size of 25634 bytes compared to version 0.6.6's 25505 bytes. This increment, while modest, suggests potential refinements or additions to the codebase. The "fileCount" remains consistent at 6, indicating that the number of files in the package didn't change between releases, so the size difference is more likely from content.
The release dates are also within the same day. If you had 0.6.6 be sure to look at the changelog, since something changed in a very short time and could imply the fix (or adition) of something important.
For developers considering esbuild, both versions represent excellent choices for tasks demanding rapid build times. When selecting between 0.6.6 and 0.6.7, it's advisable to consult the official esbuild changelog or release notes to understand the specific modifications incorporated in the newer version and determine if they address particular needs or potential issues encountered in the previous iteration. This package offers a compelling solution for optimizing the JavaScript build process, delivering performance gains and streamlining development workflows.
All the vulnerabilities related to the version 0.6.7 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.