Esbuild, a blazing-fast JavaScript and CSS bundler and minifier, has seen a recent update with the release of version 0.19.7, succeeding the previous stable version 0.19.6. While both versions share the same core description, license (MIT), and repository details, the key difference lies in their version numbers and the release dates. Version 0.19.7 was released on November 21, 2023, whereas version 0.19.6 was released on November 19, 2023.
Both versions list identical dependencies and optional dependencies, including platform-specific builds for various architectures like Linux, Windows, macOS (Darwin), Android, and more. These dependencies, named with the format @esbuild/{platform}-{architecture}, are versioned to match the core esbuild package version, ensuring compatibility across different environments. The architecture support is extensive and incorporates less common targets like FreeBSD, OpenBSD, and several ARM and RISC-V variants, showcasing esbuild's commitment to broad compatibility.
From a developer's perspective, this update means a potential for bug fixes, performance improvements, or minor feature enhancements that differentiate 0.19.7 from 0.19.6. While the provided data doesn't explicitly outline the changes, upgrading to the latest version is recommended to benefit from any recent optimizations and fixes. The small difference in unpacked size suggests potential fine-tuning improving resource usage. If you are currently using version 0.19.6, upgrading to 0.19.7 might be worthwhile to leverage the latest improvements within the esbuild ecosystem.
All the vulnerabilities related to the version 0.19.7 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.