Esbuild version 0.13.6 represents a minor update over the previous stable version, 0.13.5, primarily focused on distributing updated pre-built binaries for different operating systems and architectures. Specifically, both versions include a comprehensive set of pre-compiled binaries tailored for various platforms including Linux (32-bit, 64-bit, ARM, ARM64, PPC64le, and MIPS64le), Windows (32-bit, 64-bit, and ARM64), macOS (64-bit and ARM64), FreeBSD (64-bit and ARM64), NetBSD (64-bit), OpenBSD (64-bit), SunOS (64-bit), and Android (ARM64). This wide range of support allows esbuild to function efficiently across diverse environments without requiring compilation from source.
The core functionality and API of esbuild likely remain consistent between the two versions, meaning developers can upgrade from 0.13.5 to 0.13.6 seamlessly without anticipated breaking changes. The difference in unpackedSize between the two versions are quite minimal and suggests that only the version numbers inside the different dependencies or very minor changes has been performed. Developers should consider upgrading to version 0.13.6 to leverage these updated binaries, potentially benefiting from performance improvements or bug fixes specific to certain platforms indirectly introduced by the bundled dependencies (esbuild-\* packages). The dependencies and optional dependencies lists are identical except by their version number, which implies each dependency has been recompiled to match the version of esbuild. Especially relevant for developers targeting unusual or embedded architectures, ensuring they have the latest platform-specific optimizations. The release date also denotes a very recent change, indicating that it incorporates the most current refinements available.
All the vulnerabilities related to the version 0.13.6 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.