Esbuild 0.15.7 is a minor release, succeeding version 0.15.6, in the rapid evolution of this extremely fast JavaScript and CSS bundler and minifier. While both versions share the same core description, MIT license, and repository, a closer look reveals some key differences useful for developers. The most obvious change is the version bump, indicating bug fixes and potentially small feature enhancements under the hood.
Structurally, both versions list identical dependencies and optional dependencies encompassing a wide array of platform-specific builds, catering to diverse operating systems and architectures from Linux (32-bit, 64-bit, ARM, ARM64, s390x, ppc64le, riscv64, mips64le, loong64), SunOS (64-bit), Darwin (64-bit, ARM64), NetBSD (64-bit), Android (64-bit, ARM64), FreeBSD (64-bit, ARM64), OpenBSD (64-bit) and Windows (32-bit, 64-bit, ARM64). This highlights esbuild's commitment to cross-platform compatibility, enabling developers to build applications for virtually any target environment.
The dist metadata exposes a crucial difference: unpackedSize. Version 0.15.7 comes in at 119851 bytes unpacked, a smidge larger than 0.15.6's 119818 bytes. These extra 33 bytes likely comprise bug fixes, performance tweaks, or very minor new features, the specifics of which would require deeper investigation into the esbuild changelog. Furthermore, the releaseDate confirms that 0.15.7 was released on September 4, 2022, following 0.15.6's release on August 30, 2022. Developers are encouraged to upgrade to the latest minor version (0.15.7) to benefit from the newest improvements and optimizations, particularly those addressing performance or stability.
All the vulnerabilities related to the version 0.15.7 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.