# CVE-2026-45670: Nuxt source code disclosure in webpack and rspack builders

Source: https://junglewise.ai/threats/cve-2026-45670-nuxt-source-code-disclosure-in-webpack-and-rspack-builders  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-12. Updated: 2026-06-12  
License: CC BY 4.0 with a link back

CVE-2026-45670 · Severity: medium · CVSS 3.1 · Published 2026-06-12

Nuxt is a popular web development framework. A security flaw in its development tools could allow a malicious website to steal a developer's source code if they are running a development server on their local network. This occurs when the developer hosts their project on a non-private address and visits a compromised site, potentially exposing intellectual property or sensitive configuration details.

Technologies: [@nuxt/rspack-builder (npm)](https://junglewise.ai/threats/technologies/nuxt-rspack-builder), [@nuxt/webpack-builder (npm)](https://junglewise.ai/threats/technologies/nuxt-webpack-builder), [Nuxt Rspack Builder](https://junglewise.ai/threats/technologies/rspack-builder), [Nuxt Webpack Builder](https://junglewise.ai/threats/technologies/webpack-builder). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [Nuxt](https://junglewise.ai/threats/vendors/nuxt).

## Quick answers

**Is CVE-2026-45670 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-45670 being exploited in the wild.

**How severe is CVE-2026-45670?** Medium severity, with a CVSS score of 3.1, published 12 June 2026.

**Which products and versions are affected?** @nuxt/rspack-builder (npm) SEMVER:introduced=3.15.4,fixed=3.21.6; @nuxt/webpack-builder (npm) SEMVER:introduced=3.15.4,fixed=3.21.6; Nuxt Rspack Builder >= 3.15.4, <= 3.21.5; >= 4.0.0-alpha.1, <= 4.4.5, 3.15.4 to < 3.21.6, 4.0.0-alpha.1 to < 4.4.6; Nuxt Webpack Builder >= 3.15.4, <= 3.21.5; >= 4.0.0-alpha.1, <= 4.4.5, 3.15.4 to < 3.21.6, 4.0.0-alpha.1 to < 4.4.6.

**Is there a fix for CVE-2026-45670?** Yes. @nuxt/rspack-builder (npm): upgrade to 3.21.6 or later; @nuxt/webpack-builder (npm): upgrade to 3.21.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-45670 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-45670?** Check whether you run @nuxt/rspack-builder (npm), @nuxt/webpack-builder (npm), Nuxt Rspack Builder or one of the others listed 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

- @nuxt/rspack-builder (npm): upgrade to 3.21.6 or later

  ```sh
  npm install @nuxt/rspack-builder@3.21.6
  ```

- @nuxt/webpack-builder (npm): upgrade to 3.21.6 or later

  ```sh
  npm install @nuxt/webpack-builder@3.21.6
  ```


## Technical details

This vulnerability is an incomplete fix for a previous issue (GHSA-4gf7-ff8x-hq99). The original mitigation relied on 'Sec-Fetch-Mode' and 'Sec-Fetch-Site' headers to enforce same-origin checks; however, browsers do not send these headers for non-trustworthy origins (such as plain IP addresses on a local network). If a developer runs 'nuxt dev --host' and visits a malicious site, the attacker can use a script tag to load the application bundle and extract source code using 'Function.prototype.toString' on the webpack/rspack chunk global. The vulnerability is patched in versions 3.21.6 and 4.4.6 by falling back to 'Origin', 'Referer', and 'Host' header comparisons when 'Sec-Fetch' headers are missing.

## Affected products

- Nuxt @nuxt/rspack-builder 3.15.4 to < 3.21.6, 4.0.0-alpha.1 to < 4.4.6
- Nuxt @nuxt/webpack-builder 3.15.4 to < 3.21.6, 4.0.0-alpha.1 to < 4.4.6

## Identifiers

- CVE-2026-45670
- GHSA-6m52-m754-pw2g

## Timeline

- 2025-01-24: advisory: Original vulnerability GHSA-4gf7-ff8x-hq99 disclosed
- 2026-05-11: patched: Fix merged in PR #35051
- 2026-06-12: disclosed: CVE-2026-45670 published

## References

- [https://github.com/nuxt/nuxt/pull/35051](https://github.com/nuxt/nuxt/pull/35051)
- [https://github.com/nuxt/nuxt/security/advisories/GHSA-4gf7-ff8x-hq99](https://github.com/nuxt/nuxt/security/advisories/GHSA-4gf7-ff8x-hq99)
- [https://github.com/nuxt/nuxt/security/advisories/GHSA-6m52-m754-pw2g](https://github.com/nuxt/nuxt/security/advisories/GHSA-6m52-m754-pw2g)

## Related threats

- [Nuxt source code disclosure in webpack and rspack builders](https://junglewise.ai/threats/cve-2026-49993-nuxt-source-code-disclosure-in-webpack-and-rspack-builders)
- [Nuxt webpack/rspack dev server source code disclosure via CORS](https://junglewise.ai/threats/cve-2025-24361-nuxt-webpack-rspack-dev-server-source-code-disclosure-via-cors)