Esbuild version 0.14.6 builds upon the solid foundation laid by version 0.14.5, offering developers a seamlessly fast JavaScript and CSS bundling and minification experience. The core functionality remains consistent, ensuring backward compatibility and a smooth upgrade process. Both versions share identical dependencies and optional dependencies, covering a comprehensive range of operating systems and architectures, including Linux (32-bit, 64-bit, ARM, ARM64, PPC64le, MIPS64le), macOS (64-bit and ARM64), Windows (32-bit, 64-bit, ARM64), FreeBSD (64-bit and ARM64), NetBSD, OpenBSD, SunOS, and Android (ARM64). This broad support caters to diverse development environments.
The key distinction lies in the release date, with version 0.14.6 arriving on December 20, 2021, after version 0.14.5 released on December 14, 2021. While the unpacked size and file count remain constant, this update likely incorporates bug fixes, performance enhancements, or minor feature adjustments not explicitly detailed in the package metadata. Developers are encouraged to review the official esbuild changelog or release notes for a comprehensive list of changes. For users seeking the most recent bug fixes and incremental improvements within the stable 0.14.x series, upgrading to version 0.14.6 is generally recommended. The MIT license and consistent repository URL guarantee the continued open-source accessibility and maintainability of esbuild.
All the vulnerabilities related to the version 0.14.6 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.