Esbuild, a lightning-fast JavaScript and CSS bundler and minifier, has a new version available. Upgrading from version 0.13.11 to 0.13.12 brings subtle but essential updates. The core functionality remains consistent, ensuring a smooth transition for existing users. Both versions are licensed under the MIT license and maintained in the same GitHub repository.
The key difference lies within the dependencies. Both the dependencies and optionalDependencies fields have been bumped across the board, with all the platform-specific packages like esbuild-linux-64, esbuild-darwin-arm64, and esbuild-windows-64 updated from version 0.13.11 to 0.13.12. This implies that internal bug fixes, performance improvements, or support for new operating system features are likely included within these platform-specific binaries. While the fileCount remains consistent at 6, the unpackedSize decreased slightly from 104558 bytes to 104366 bytes, suggesting slight optimization in the packaged binaries.
The later release date, October 31, 2021, compared to October 30, 2021, of version 0.13.11 implies this is a patch update addressing potentially critical issues found in the previous version. For developers using esbuild, upgrading is advised to benefit from these refinements and ensure optimal performance and stability across all supported platforms. Although not explicitly stated, carefully reviewing the changelog on the esbuild GitHub repository, is highly recommended to understand the specific details and impact of these changes.
All the vulnerabilities related to the version 0.13.12 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.