Esbuild, an extremely fast JavaScript and CSS bundler and minifier, saw a minor version update from 0.14.0 to 0.14.1. While both versions share the same core description, license (MIT), repository URL, file count (6), and unpacked size (104346 bytes), the key difference lies in the versioning of their dependencies and their release dates. Both versions have all the same dependencies and optional dependencies from the esbuild-* family referring to different OS and architecture targets. These dependencies ensure esbuild's compatibility across a wide range of platforms, including Linux (32-bit, 64-bit, ARM, ARM64, ppc64le, mips64le), SunOS (64-bit), Darwin (64-bit, ARM64), NetBSD (64-bit), FreeBSD (64-bit, ARM64), OpenBSD (64-bit), Windows (32-bit, 64-bit, ARM64), and Android (ARM64). The dependencies and optional dependencies are identical across both versions, but they point to their respective package versions.
Version 0.14.1 was released on November 30, 2021, while version 0.14.0 was released a few days earlier on November 26, 2021. For developers, this update represents a minor iteration, likely addressing bug fixes or small enhancements rather than introducing significant new features. When upgrading, developers should always review changelogs or release notes (available on the esbuild GitHub repository) for a comprehensive understanding of the changes. Given the identical dependency structure, the update is likely to be straightforward with minimal risk of compatibility issues. Always test your build process after updating any dependency.
All the vulnerabilities related to the version 0.14.1 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.