Esbuild version 0.1.23 represents a minor iteration over its predecessor, version 0.1.22, in the rapidly evolving world of JavaScript bundling and minification. Both versions share the core promise of Esbuild: providing developers with an exceptionally fast solution for preparing their JavaScript code for production. Evidenced by their identical descriptions, file counts (6), unpacked sizes (8647), license (MIT), and repository, the fundamental functionality remains consistent.
The primary difference lies in their release dates. Version 0.1.23 was published on May 3rd, 2020, at 23:27:41 UTC, approximately 14 hours after version 0.1.22, which was released on the same day at 09:27:36 UTC. This suggests that the update likely addresses bug fixes, performance enhancements, or minor feature tweaks discovered after the initial release of 0.1.22.
For developers, this indicates that upgrading from 0.1.22 to 0.1.23 is likely a safe and recommended move. The similarity between the versions means minimal risk of breaking changes, while the later release date hints at improved stability and potential refinements. While the specific nature of the changes isn't explicitly stated here, the short timeframe between releases points towards iterative improvements that contribute to a smoother and more efficient bundling experience. Developers seeking optimal performance and stability in their JavaScript build processes should, therefore, favor the newer version.
All the vulnerabilities related to the version 0.1.23 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.