Esbuild 0.13.15 is a minor release of the blazing-fast JavaScript and CSS bundler and minifier, building upon the capabilities of version 0.13.14. Both versions share the same core description: an extremely fast tool for bundling and minifying web assets. The key distinction lies in the dependency versions. While both versions depend on and optionally depend on a suite of platform-specific esbuild binaries (like esbuild-linux-64, esbuild-windows-64, etc.), version 0.13.15 updates these dependencies to their respective "0.13.15" versions, ensuring consistency and potential bug fixes specific to those platform binaries.
For developers, this means upgrading from 0.13.14 involves receiving the latest platform-specific optimizations and potentially important fixes implemented in the 0.13.15 binaries. The core functionality of esbuild, known for its speed and ease of use, remains consistent, offering developers a streamlined experience for bundling their JavaScript and CSS code for production. The release date difference also suggests a focus on maintenance and continued improvement by the esbuild team. Both versions are licensed under the MIT license. The unpacked size of the package is the same for both versions and the file count in the archive is the same too. The repository for both continues to be the official github repository.
All the vulnerabilities related to the version 0.13.15 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.