Esbuild version 0.13.9 is a minor update to the extremely fast JavaScript and CSS bundler and minifier, building upon the foundation laid by version 0.13.8. The core functionality remains the same, focusing on unparalleled build speeds and efficient code optimization vital for modern web development workflows.
The key difference lies within the dependency versions. Both versions bundle pre-built binaries for a wide range of platforms (Linux, Windows, macOS, FreeBSD, OpenBSD, NetBSD, SunOS) and architectures (32-bit, 64-bit, ARM, ARM64, PPC64le, MIPS64le), ensuring compatibility across diverse environments. However, version 0.13.9 updates these platform-specific binaries (esbuild-linux-64, esbuild-windows-64, etc.) from version 0.13.8 to 0.13.9. This suggests that the update likely includes bug fixes, performance improvements, or security patches targeted specifically at those binaries, rather than changes to the core bundler code.
For developers, this means that upgrading to 0.13.9 is recommended to benefit from the latest stability and performance improvements in the platform-specific builds. While the API and core bundling behavior likely remain consistent, ensuring that you are running the newest versions of these dependencies is crucial for robust and reliable builds, particularly when targeting a specific platform or architecture. The unpacked size increased nominally from 99927 to only 99959, so its usage impact should be negligible.
All the vulnerabilities related to the version 0.13.9 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.