Esbuild versions 0.12.27 and 0.12.28 offer developers an incredibly fast JavaScript bundler and minifier, streamlining the build process for web applications. Both versions share the same fundamental features, MIT license, git repository, number of files and unpacked size. The core functionality remains consistent, providing efficient bundling and minification capabilities.
The primary difference lies in their release dates. Version 0.12.28 was released on September 14, 2021, roughly a day after version 0.12.27, which was released on September 13, 2021. This suggests that version 0.12.28 likely contains bug fixes, minor improvements, or quick patches addressing issues discovered in the preceding release.
For developers choosing between these specific versions, it is generally advisable to opt for the newer version 0.12.28. The updated release typically offers the most stable and reliable experience, incorporating refinements and remedies to enhance performance and address potential vulnerabilities. Upgrading ensures access to the latest improvements and provides a smoother development workflow when leveraging esbuild for JavaScript bundling and minification.
All the vulnerabilities related to the version 0.12.28 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.