Esbuild versions 0.5.11 and 0.5.12 are both fast JavaScript bundlers and minifiers, identified by their efficiency and speed in processing JavaScript code. Both versions are MIT licensed, ensuring freedom in usage and distribution, and share the same repository. Each package contains six files and unpacks to a size of 19983 bytes. These attributes indicate a relatively lightweight tool, contributing to its speed, and suggests that the core functionality and size haven't significantly changed between the releases.
The primary difference lies in their release dates. Version 0.5.12 was released on June 24, 2020, while version 0.5.11 was released on June 23, 2020. This indicates that the update from 0.5.11 to 0.5.12 was very recent.
While the details do not offer specific changes between the versions, the quick subsequent release of version 0.5.12 suggests it likely addresses minor bugs, performance improvements, or very targeted feature enhancements introduced in the previous version 0.5.11. For developers utilizing esbuild, upgrading to the latest version is generally recommended to benefit from these rapid iterations and improvements in stability or functionality. Developers should explore the projects changelog for exact details of the changes if specifics are needed to update. The fast release cadance shows the project is active and being maintained to a high degree.
All the vulnerabilities related to the version 0.5.12 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.