Esbuild version 0.11.9 represents a minor iteration over its predecessor, version 0.11.8. Both versions maintain the core promise of esbuild as an exceptionally fast JavaScript bundler and minifier, licensed under the permissive MIT license, ensuring flexibility for developers. The fundamental characteristics, such as repository location and package structure reflected in the fileCount and unpackedSize within the dist object—remain constant between the two versions. This indicates no significant structural change or major code refactoring happened between them.
The primary difference lies in their release dates. Version 0.11.9 was published on April 12, 2021, shortly after version 0.11.8 which was released on April 11, 2021. This close proximity suggests that 0.11.9 likely addresses a bug fix or a minor enhancement identified soon after the release of 0.11.8. For developers, this signals the importance of upgrading to the latest patch version to benefit from the most current stability improvements.
While the provided data doesn't explicitly detail the specific changes, users are always encouraged to examine the changelog on the official esbuild GitHub page to understand precise fixes or enhancements introduced. Utilizing up-to-date bundlers like esbuild ensures optimal performance and often includes the latest ECMAScript standard support, contributing to streamlined modern web development workflows. Therefore adopting version 0.11.9 is generally advisable, ensuring a smoother experience for building and deploying web applications, especially concerning edge cases and minor bugs fixed post 0.11.8 release.
All the vulnerabilities related to the version 0.11.9 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.