Esbuild versions 0.1.23 and 0.1.24 represent incremental updates to this extremely fast JavaScript bundler and minifier. Both versions share the same core description, MIT license, and source code repository on GitHub. They are packaged as tarballs available on the npm registry. The key difference lies in the release date and potentially the included bug fixes, performance improvements, or minor feature additions. Version 0.1.24 was released on May 4th, 2020, shortly after version 0.1.23 released on May 3rd, 2020, suggesting a quick follow-up release.
A subtle difference also exists in the unpacked size, with version 0.1.24 being slightly larger at 8702 bytes compared to version 0.1.23's 8647 bytes. This points towards code modifications or additions that caused the size increase.
For developers considering esbuild, this information highlights the rapid development cycle and commitment to improvement. While the changes between these specific versions may be minor, the fact that a new version arrived quickly indicates an active project. Developers should review the esbuild changelog or commit history on GitHub between these dates to understand the detailed changes and how they might affect their projects.
All the vulnerabilities related to the version 0.1.24 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.