Esbuild versions 0.11.1 and 0.11.2 are both fast JavaScript bundlers and minifiers designed to streamline web development workflows. Both are released under the MIT license, and hosted on GitHub. They share identical descriptions, file counts (6), unpacked sizes (81010), and repository information, indicating a very similar core architecture. The critical distinction between these versions lies in their release dates. Version 0.11.1 was released on March 29, 2021, while version 0.11.2 followed shortly after on March 30, 2021.
This immediate succession suggests that version 0.11.2 likely addresses a bug fix or minor enhancement identified in the earlier release. For developers considering esbuild, this signifies a need to prioritize version 0.11.2. While both versions offer the benefits of esbuild's speed and efficiency in bundling and minifying JavaScript code for faster load times and improved performance, the newer release will probably include important fixes. Upgrading to 0.11.2 is generally recommended to ensure a more stable and reliable experience, especially when adopting a new tool in the production environment. Always review the changelog or release notes (typically found in the GitHub repository) for detailed insights into the specific changes implemented between these versions.
All the vulnerabilities related to the version 0.11.2 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.