Esbuild versions 0.1.6 and 0.1.7 are both iterations of an extremely fast JavaScript bundler and minifier, designed to accelerate the build process for web applications. Both versions are licensed under the permissive MIT license, making esbuild a cost-effective choice for projects of any size. Maintained in a GitHub repository by evanw, the tool benefits of a centralized version control.
While both versions share the same core functionality, description, license, repository, fileCount and unpackedSize. The key difference between versions 0.1.6 and 0.1.7 lies in their release dates. Version 0.1.6 was released on April 16, 2020, at 04:58:41 UTC, while version 0.1.7 followed later the same day at 17:44:22 UTC. This suggests that version 0.1.7 likely contains bug fixes or minor enhancements implemented after the initial 0.1.6 release.
For developers considering esbuild, this speed increase translates to faster development cycles and improved productivity. Esbuild's ability to handle large codebases efficiently reduces waiting times, allowing developers to focus on coding. The choice between the two lies in the priority developers place on incorporating the latest bug fixes and incremental improvements versus sticking with a previously tested version. Nevertheless, both versions represent a commitment to providing performant and developer-friendly solutions.
All the vulnerabilities related to the version 0.1.7 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.