Esbuild, a blazing-fast JavaScript bundler and minifier, saw a minor version bump from 0.13.0 to 0.13.1, offering subtle yet potentially impactful improvements for developers. Both versions share the core functionality of efficiently bundling and minifying JavaScript code, boasting impressive speed compared to other tools in the ecosystem. They also maintain identical dependency structures, relying on a suite of platform-specific packages (e.g., esbuild-linux-64, esbuild-windows-64) to provide native binaries tailored for various operating systems and architectures. This ensures optimal performance regardless of the target environment.
While the feature set remains largely consistent between the two versions, the upgrade to 0.13.1 likely incorporates bug fixes and minor internal optimizations. A key difference lies in the increased unpackedSize, a reflection of possible code enhancements or the inclusion of more detailed debugging information. Developers should consider upgrading to version 0.13.1 to potentially benefit from these refinements and ensure they are using the most stable and up-to-date release. The later releaseDate also confirms that 0.13.1 is the newer and likely more polished build. Always check official release notes for a full list of changes.
All the vulnerabilities related to the version 0.13.1 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.