Esbuild versions 0.5.17 and 0.5.18 are both extremely fast JavaScript bundlers and minifiers, designed to significantly improve build times for web developers. Both versions are licensed under the MIT license and share the same core functionality, aiming to provide a blazing-fast alternative to traditional JavaScript bundling tools. The package contents and unpacked size remain identical between the two releases, each consisting of six files and occupying 20.14 KB.
The key difference between these versions lies in their release dates. Version 0.5.18 was published on July 2, 2020, at 10:50:16.358Z, while version 0.5.17 was released earlier on the same day at 06:57:19.679Z. While the changelog is not available in the provided data, the time difference likely indicates bug fixes or minor improvements incorporated in version 0.5.18.
For developers considering esbuild, either version offers substantial performance benefits, especially for large projects. The tool excels at bundling and minifying JavaScript, TypeScript, and other web assets with remarkable speed. When choosing between these specific versions, opting for 0.5.18 is advisable, presuming it addresses any immediate issues present in 0.5.17, even though the provided data lacks explicit details. Always check the project's official release notes for comprehensive details regarding the updates and bug fixes included within each version.
All the vulnerabilities related to the version 0.5.18 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.