Esbuild versions 0.12.11 and 0.12.12 represent incremental updates to this blazing-fast JavaScript bundler and minifier. Both versions maintain the core functionality that developers rely on for efficient builds, sharing the same MIT license, repository location, unpacked size, and file count, which underscores the stability of the tool. The key distinction between the two lies in their release dates. Version 0.12.12 came out roughly 17 hours after version 0.12.11.
While the underlying code base remains largely consistent between these versions, the slight gap in release time often signals bug fixes or minor adjustments made following the initial release of 0.12.11. Developers who prioritize stability and seek the most up-to-date fixes within the 0.12.x series would benefit from upgrading to 0.12.12 to ensure they have the latest improvements. For those already using 0.12.11, the upgrade path is likely seamless due to the small change sets. Esbuild's focus on performance and its simple API makes it perfect for building modern web applications and libraries while speeding up deployment pipelines.
All the vulnerabilities related to the version 0.12.12 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.