Esbuild versions 0.12.18 and 0.12.19 represent incremental updates to this extremely fast JavaScript bundler and minifier, a tool favored by developers seeking performance improvements in their build processes. Both versions share the same core characteristics: MIT licensing, accessibility through the official GitHub repository, and similar distribution packages with identical file counts (6) and unpacked sizes (88,875 bytes). This highlights consistency in the project's structure and distribution method.
The primary distinction lies in their release dates. Version 0.12.19 was published on August 7, 2021, while version 0.12.18 was released on August 5, 2021. This two-day gap suggests that 0.12.19 likely contains bug fixes, performance enhancements, or minor feature additions implemented after the release of 0.12.18.
For developers, staying up-to-date with esbuild ensures access to the latest optimizations and resolutions. While the core functionality remains consistent between these two versions, upgrading to 0.12.19 is recommended to benefit from any improvements made within that short timeframe. Developers should consult the official esbuild changelog for a detailed list of specific changes in each release to understand the specific benefits of upgrading and whether these changes align with the particular needs of the project. Using the most recent version helps ensure projects benefit from the ongoing commitment to performance and stability.
All the vulnerabilities related to the version 0.12.19 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.