Esbuild version 0.14.33 is a minor release update to the extremely fast JavaScript and CSS bundler and minifier, building upon the solid foundation of version 0.14.32. At its core, esbuild remains a powerful tool for developers seeking optimized build processes. Both versions share the same fundamental dependencies, each tailored to specific operating systems and architectures, from Linux 32-bit to Windows ARM64, ensuring broad compatibility. This extensive platform support makes esbuild a versatile choice for diverse development environments.
While the core functionality and dependencies remain consistent between versions 0.14.32 and 0.14.33, the subtle changes under the hood likely involve bug fixes, performance enhancements, or minor feature adjustments. Developers considering an upgrade should be aware that the file count (6) and unpacked size (117438 bytes) are identical, suggesting that the code changes are contained within existing files or represent very small additions. The release date difference indicates active maintenance, which is crucial for ensuring stability and addressing potential security vulnerabilities. For existing users, upgrading to 0.14.33 is probably a safe bet, providing incremental improvements; new adopters will benefit from a more recent version incorporating community feedback and potentially a smoother setup process. The MIT license continues to make the tool free and usable in various open source and commercial projects.
All the vulnerabilities related to the version 0.14.33 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.