Esbuild 0.17.3 represents a minor version update over 0.17.2 in the popular JavaScript and CSS bundler and minifier. Both versions share the same core description, emphasizing esbuild's primary goal of extreme speed. Examining their metadata reveals subtle differences primarily related to the versions of platform-specific binaries included as dependencies and optional dependencies. Specifically, all listed platform-specific packages like @esbuild/linux-x64, @esbuild/win32-arm64, and others, within both dependencies and optionalDependencies, have been updated from version 0.17.2 to 0.17.3.
For developers, this means the update likely incorporates bug fixes and performance improvements within the pre-built binaries tailored for various operating systems and architectures. While the core API and functionality of esbuild probably remain consistent, upgrading to 0.17.3 ensures access to the latest optimizations and potentially crucial fixes relating to platform compatibility and stability. The releaseDate also confirms 0.17.3 was released shortly after 0.17.2, hinting that the changes might be relatively focused and addressing immediate issues discovered in the prior release. Developers should consider upgrading to benefit from these under-the-hood enhancements and maintain optimal build performance across different environments. Check the esbuild changelog for more detailed info.
All the vulnerabilities related to the version 0.17.3 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.