Esbuild 0.12.9 and 0.12.8 offer developers an exceptionally fast JavaScript bundler and minifier, ideal for speeding up build times and optimizing web application performance. Both versions share the same core features, including MIT licensing, a Git repository at GitHub provided by evanw, a concise file count of 6, and an identical unpacked size of 88440 bytes. This shared foundation underscores the stability and consistent design principles of the esbuild project.
The primary distinction between these versions lies in their release dates. Version 0.12.9 was released on June 16, 2021, while version 0.12.8 was released on June 9, 2021. While the core functionality remains consistent, the 0.12.9 release likely incorporates bug fixes, performance improvements, or minor feature enhancements implemented in the week between releases.
For developers, choosing between these versions depends on their specific needs. If staying on the absolute cutting edge with potentially the latest fixes is a priority, esbuild 0.12.9 is preferable. Those prioritizing utmost stability and seeking to avoid any potential (albeit unlikely) regressions may opt for esbuild 0.12.8. Given the rapid development cycle and the minor version difference, most developers will find either version a reliable and performant choice for bundling and minifying their JavaScript code, as these packages provides the exact same files, as the fileCount and unpackedSize are equals.
All the vulnerabilities related to the version 0.12.9 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.