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, = 4.0.0-alpha.1, = 3.15.4, = 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.

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

Q: 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.

Q: How is CVE-2026-45670 attacked?

It is attacked from the adjacent network, in a software library.

Q: 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.

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), @nuxt/webpack-builder (npm), Nuxt Rspack Builder, Nuxt Webpack Builder. Vendors: npm, 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
```
npm install @nuxt/rspack-builder@3.21.6
```
@nuxt/webpack-builder (npm): upgrade to 3.21.6 or later
```
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

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