Esbuild is a JavaScript bundler and minifier known for its exceptional speed. Comparing versions 0.1.11 and 0.1.12, we observe minimal differences in terms of core metadata. Both versions share the same description, MIT license, repository URL, file count (3), and unpacked size (2463 bytes). The key distinction lies in their release dates. Version 0.1.12 was released shortly after 0.1.11, specifically on April 19, 2020, at 23:02:52.179Z, while version 0.1.11 was released on the same day at 22:26:29.895Z.
For developers, this small time gap suggests that version 0.1.12 likely contains bug fixes or minor improvements implemented immediately after the release of 0.1.11. While the exact nature of these changes isn't explicitly detailed in the provided data, the rapid succession implies a quick response to issues discovered in the earlier version. Therefore, developers seeking the most stable and up-to-date experience are generally advised to use the newer version (0.1.12) to benefit from these potential refinements. Always consult the official esbuild changelog or repository for comprehensive release notes detailing the specific modifications. The tarball URLs provided allow direct access to the package files for installation, ensuring a smooth integration into development workflows.
All the vulnerabilities related to the version 0.1.12 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.