Esbuild version 0.14.49 is a patch release following closely on the heels of version 0.14.48 of this popular JavaScript and CSS bundler and minifier. Both versions share the same core description, promising extremely fast performance for bundling and minifying web assets. The most notable difference lies in the version numbers of their dependencies, particularly the platform-specific binary packages like esbuild-linux-64, esbuild-windows-64, and others that target diverse operating systems and architectures. Each of these dependencies is bumped from version 0.14.48 to 0.14.49, indicating that the patch likely contains bug fixes, performance enhancements, or compatibility updates within these platform-specific binaries.
For developers, this suggests an upgrade to 0.14.49 is worthwhile, especially if they encountered platform-specific issues with 0.14.48 or are seeking the most stable and optimized build. The core functionality remains consistent, so the upgrade should be seamless. The release dates also highlight the recency of both versions, with 0.14.49 released just over a week after 0.14.48. This rapid iteration cycle demonstrates the ongoing development and commitment to providing a robust and reliable tool. If your project depends on esbuild, keeping up with these minor version bumps ensures you're benefiting from the latest improvements and mitigating potential risks.
All the vulnerabilities related to the version 0.14.49 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.