Esbuild version 0.13.11 represents a minor update over its predecessor, 0.13.10, in the realm of fast JavaScript and CSS bundling and minification. While the core functionality and mission of providing an extremely speedy build process remain consistent, developers should note the subtle differences in package versions within the dependencies and optional dependencies. Specifically, all platform-specific esbuild binaries (like esbuild-linux-64, esbuild-darwin-arm64, esbuild-windows-64, etc.) have been bumped from version 0.13.10 to 0.13.11 to align with the main package version. This change suggests potential bug fixes, performance improvements, or platform-specific adaptations within the underlying compiled binaries.
The unpackedSize in the dist object increased slightly from 104366 to 104558, indicative of minor code additions or changes to the included binaries. The release date also highlights the recency of version 0.13.11, released just two days after 0.13.10. For developers, upgrading from 0.13.10 to 0.13.11 is recommended, especially if facing platform-specific issues or seeking the latest performance enhancements, as this micro-update incorporates potentially crucial fixes and optimizations for various operating systems and architectures without introducing breaking changes. As always, regression testing your build process after the update is sound practice.
All the vulnerabilities related to the version 0.13.11 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.