Esbuild version 0.12.24 is a minor update to the lightning-fast JavaScript bundler and minifier, following closely on the heels of version 0.12.23. Both versions share the same core characteristics: blazing speed, MIT license, and the same unpacked size of 89145 bytes across 6 files, as well as the same repository location. The key difference lies in the release date. Version 0.12.24 was published on August 27, 2021, while version 0.12.23 arrived just a day prior, on August 26, 2021.
For developers, this suggests that version 0.12.24 likely includes bug fixes or minor enhancements discovered shortly after the release of 0.12.23. While the changelog specifics would be crucial for a complete understanding, the rapid succession of releases highlights the ongoing commitment to stability and performance. Developers already using ESBuild should investigate the differences between the two versions, to get the latest features and enhancement. Given the minimal time difference, upgrading from 0.12.23 to 0.12.24 is recommended to ensure access to the most current and potentially improved iteration of this popular bundler. New projects should, preferrably use the latest release, as that version contains bug-fixes and small improvements over the older version.
All the vulnerabilities related to the version 0.12.24 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.