Esbuild versions 0.12.21 and 0.12.22 are both iterations of an extremely fast JavaScript bundler and minifier, known for its exceptional performance compared to other tools in the ecosystem. Aimed at streamlining the build process for web developers, esbuild is released under the MIT license and maintained on GitHub, offering transparency and community involvement.
While seemingly similar, as indicated by identical file counts (6) and unpacked sizes (88920 bytes) in their respective distributions, the key difference between these versions lies in their release dates. Version 0.12.22 was published on August 21, 2021, while version 0.12.21 was released just days prior on August 18, 2021. This temporal gap suggests that 0.12.22 likely incorporates bug fixes, minor enhancements, or performance tweaks discovered after the release of 0.12.21.
For developers seeking the most up-to-date and potentially stable experience, version 0.12.22 would be the preferred choice. Staying current with the latest minor releases is crucial to benefit from the continuous improvements the esbuild team ships. While the core functionality of the bundler likely remains consistent between these versions, the newer release provides a potentially more polished build process, leading to faster compile times and fewer unexpected issues in production deployments. Therefore, upgrading to version 0.12.22 is recommended to leverage the latest refinements.
All the vulnerabilities related to the version 0.12.22 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.