Esbuild 0.15.13 is a minor version update to the blazing-fast JavaScript and CSS bundler, following closely on the heels of version 0.15.12. The core functionality and feature set remain consistent between the two versions, ensuring a seamless transition for developers already utilizing esbuild. The primary difference lies in the updated dependency versions. Both versions share the same architecture which relies on platform specific "sub-packages" to achieve their speed, that is why they list all those "esbuild-*" dependencies.
Crucially, all dependencies, which are platform-specific binaries such as esbuild-linux-64 and esbuild-windows-64, have been bumped from version 0.15.12 to 0.15.13. This indicates that the update likely includes bug fixes, performance improvements, or security patches within these platform-specific builds. The core esbuild logic, accessible through the main esbuild package, likely remains unchanged.
For developers, this means updating from 0.15.12 to 0.15.13 is a low-risk operation with the potential for improvements in stability and performance, especially if the application is deployed accross different enviroments. Given the nature of esbuild as a build tool deeply integrated into development workflows, staying up-to-date with these minor releases is generally recommended to benefit from the latest refinements and ensure compatibility with evolving platform requirements. The releaseDate difference also points to the fact that this could fix some new bugs on new platforms.
All the vulnerabilities related to the version 0.15.13 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.