Esbuild version 0.16.7 is a minor release over the previous stable version 0.16.6 of this extremely fast JavaScript and CSS bundler and minifier. Both versions share identical descriptions, licensing under MIT, and repository information, pointing to the same Git repository. The core functionality and purpose of the library remain unchanged, focused on providing developers with a performant tool for bundling and minifying web assets.
The key difference lies in the version numbers of the dependencies and the release dates. Both dependencies and optionalDependencies were bumped from "0.16.6" to "0.16.7". If you directly depend upon any of the mentioned OS-specific dependencies, this upgrade is necessary. The newer version was released on December 14, 2022, at 22:47:38.527Z, while version 0.16.6 was released earlier the same day. The "unpackedSize" attribute observed a slight increase to 123183 from 123167. Although seemingly the same, the bump in the version suggests that internal bug fixes and improvements were introduced so upgrading is always recommended if you are at the start of a project. For existing projects, consider checking the changelog to evaluate whether an upgrade is justified, analyzing the trade-offs.
All the vulnerabilities related to the version 0.16.7 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.