Esbuild version 0.5.23 is a minor release following 0.5.22 in the popular JavaScript bundler and minifier known for its exceptional speed. Both versions maintain the same core description: "An extremely fast JavaScript bundler and minifier," licensed under MIT and hosted on GitHub. The key difference lies in the details of their distribution packages.
While both versions consist of 6 files, esbuild 0.5.23 has a slightly larger unpacked size of 21950 bytes, compared to 21882 bytes in version 0.5.22. This suggests subtle internal changes or additions, possibly bug fixes, performance improvements, or minor feature enhancements bundled within the newer version.
Another notable difference is the release date. Esbuild 0.5.23 was released on July 6, 2020, at 10:01:33.897Z, roughly five hours after version 0.5.22, which was released at 04:59:26.778Z on the same day.
For developers, these subtle differences matter. Updating from 0.5.22 to 0.5.23 is recommended, as it likely incorporates improvements addressing previously existing issues or optimizes performance. The small size difference suggests no radical changes, so the upgrade should be smooth and non-breaking for most users, improving stability and overall performance of your JavaScript builds. Always refer to the official esbuild changelog for comprehensive details.
All the vulnerabilities related to the version 0.5.23 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.