Esbuild 0.18.12 is a minor version update, rolling out after version 0.18.11 of this blazingly fast JavaScript and CSS bundler. The core functionalities remain consistent between the two, with both versions offering efficient bundling and minification. Key differences are primarily reflected in the version bumps of its platform-specific dependencies. All the @esbuild/* packages, covering a wide range of operating systems and architectures like Linux (arm, x64, arm64, etc.), macOS (x64, arm64), Windows (x64, arm64), Android (arm, x64, arm64) and others, have been updated from version 0.18.11 to 0.18.12.
For developers, this means the underlying esbuild binary, responsible for the heavy lifting of bundling and minification, has been updated across all supported platforms. While the change might not introduce new features or breaking changes from a high-level API perspective, it likely incorporates bug fixes, performance improvements, or compatibility adjustments specific to each platform. Therefore, upgrading to 0.18.12 ensures you're leveraging the latest platform-specific optimizations and stability enhancements. Given the identical file count and unpacked size in the dist section, the update focuses on internal improvements rather than structural changes to the package. Esbuild remains a solid choice for developers seeking a rapid build tool with broad platform support. The release date difference highlights an active maintenance cycle, encouraging users to stay current with the latest version for optimal performance.
All the vulnerabilities related to the version 0.18.12 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.