Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- Low severity, with a CVSS score of 3.1, published 10 February 2025.
- Which products and versions are affected?
- esbuild (npm) SEMVER:introduced=0,fixed=0.25.0.
- Is there a fix for This vulnerability?
- Yes. esbuild (npm): upgrade to 0.25.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network.
- Am I affected?
- Check whether you run esbuild (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- esbuild (npm): upgrade to 0.25.0 or later
npm install esbuild@0.25.0
Technical details
esbuild's development server sets the Access-Control-Allow-Origin header to "*" on all responses, including Server-Sent Events (SSE) endpoints, violating proper CORS origin validation (CWE-346). An attacker can host a malicious webpage that, when visited by a developer running esbuild's serve feature, uses JavaScript fetch() to retrieve bundled code and source maps from the local development server (typically http://127.0.0.1:8000/). The attacker can discover file names by querying /index.html, directory listings, or monitoring the /esbuild SSE endpoint. The attack requires user interaction (visiting a malicious site) but no authentication or special privileges. Versions up to and including 0.24.2 are affected; the fix is available in version 0.25.0.
Affected products
- evanw esbuild <= 0.24.2
Timeline
- 2025-02-10: disclosed: Advisory GHSA-67mh-4wv8-2f99 published
- 2025-02-07: patched: Fix committed; patched in version 0.25.0