Esbuild is a blazing-fast JavaScript bundler and minifier, and versions 0.8.22 and 0.8.23 demonstrate its continued commitment to efficiency. While both versions share the same core functionality and MIT license, a closer look reveals subtle yet potentially impactful differences for developers.
Version 0.8.23, released on December 14, 2020, boasts a slightly smaller unpacked size of 60018 bytes compared to version 0.8.22's 62543 bytes, which was released on December 12, 2020. This reduction, though seemingly minor, hints at potential optimizations or bug fixes implemented in the newer version. Developers prioritizing minimal footprint and potentially improved performance should lean towards 0.8.23.
Both versions consist of 6 files and are distributed as tarballs accessible via the npm registry. The change in unpackedSize means that under the good, there were changes in the file distribution that could impact certain edge cases.
For developers already using esbuild, upgrading from 0.8.22 to 0.8.23 is recommended to benefit from any bug fixes and optimizations to the file size it may contain. While the description remains the same, the reduced size suggests an improvement that aligns with esbuild's core philosophy of speed and efficiency. New users can confidently choose the latest version (0.8.23 at the time of this data) knowing they're starting with the most refined iteration of this powerful bundler. Always check the official changelog for a comprehensive list of changes.
All the vulnerabilities related to the version 0.8.23 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.