Esbuild, a lightning-fast JavaScript bundler and minifier, saw a minor version bump from 0.5.7 to 0.5.8 with both versions sharing the same core promise of speed and efficiency for developers. Both versions are released under the MIT license, ensuring broad usability and compatibility across various projects. The package size remains consistent as reflected in the unpacked size and file count, indicating the changes between the versions might be limited to bug fixes, performance improvements, or minor feature enhancements rather than substantial additions to the codebase.
A key difference lies in their release date. Version 0.5.8 was published shortly after 0.5.7, suggesting that the changes introduced in the newer version were important enough to warrant a quick update. Developers prioritizing stability and staying on the cutting edge should check the changelog associated with version 0.5.8 to understand the specific changes and bug fixes address. The rapid release cycle signals the esbuild team's commitment to actively maintaining and refining the tool. Upgrading to version 0.5.8 can provide incremental benefits, making project builds even faster or reducing potential edge-case errors reported in older versions. Users already leveraging esbuild in their workflow should especially see if upgrading provides value.
All the vulnerabilities related to the version 0.5.8 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.