Esbuild version 0.14.27 represents a minor update over its predecessor, version 0.14.26, in this extremely fast JavaScript and CSS bundler and minifier. Examining the dependencies and optional dependencies, it's clear that both versions maintain identical platform support, with pre-built binaries available for a wide range of operating systems and architectures, including Linux (32-bit, 64-bit, ARM, ARM64, s390x, ppc64le, riscv64, mips64le), Windows (32-bit, 64-bit, ARM64), macOS (64-bit, ARM64), FreeBSD (64-bit, ARM64), NetBSD (64-bit), OpenBSD (64-bit), SunOS (64-bit), and Android (64-bit, ARM64). The core functionality and platform reach appear unchanged.
A key difference lies in the release date, with version 0.14.27 released later on March 14, 2022, compared to version 0.14.26. This suggests that the update likely incorporates bug fixes, performance improvements, or minor feature enhancements rather than a substantial overhaul. The archive unpacked size change (116734 vs 117579) indicates some changes in included files size but it's too small to suggest a meaningful modification of the functionality. Developers should consult the official esbuild changelog or release notes to understand the specific changes introduced in version 0.14.27. Given the frequent release cycle of esbuild, staying up-to-date ensures access to the most stable and optimized build tools available. Using the newest version is recommended, as it reduces risks to older versions security vulnerabilities and contains the latest fixes.
All the vulnerabilities related to the version 0.14.27 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.