Esbuild 0.19.6 represents a minor version update of the blazing-fast JavaScript and CSS bundler, building upon the foundation laid by version 0.19.5. Both versions maintain the core function of efficiently bundling and minifying code, with identical descriptions emphasizing their speed. The key difference lies in the version numbers of the platform-specific binaries contained as dependencies and optional dependencies. Each supported architecture (Linux, Windows, macOS, Android, FreeBSD, NetBSD, OpenBSD, and SunOS) across various CPU architectures (x64, ARM, ARM64, IA32, PPC64, S390x, Loong64, RISC-V 64, MIPS64el) receives an updated binary, moving from version 0.19.5 to 0.19.6, suggesting bug fixes, performance improvements, or compatibility updates within these platform-specific components.
For developers, this means that upgrading from 0.19.5 to 0.19.6 should be a seamless experience focused on getting the newest features and performance enhancements. If you're aiming to optimize the size and speed of your front-end builds and server-side JavaScript applications, Esbuild remains a compelling choice. When upgrading, it's advisable to check for any release notes or changelogs associated with version 0.19.6, if available, to understand the specifics of the updates and confirm compatibility with your existing project setup. These minor updates are typically safe and often incorporate valuable refinements, improving the overall stability and performance of your build process.
All the vulnerabilities related to the version 0.19.6 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.