CVE-2026-49993
@nuxt/webpack-builder and @nuxt/rspack-builder dev server same-origin check bypassed when Sec-Fetch-Site, Origin, and Referer are all absent (incomplete fix for GHSA-6m52-m754-pw2g)
Blast Radius
@nuxt/webpack-builder📦@nuxt/webpack-builder📦@nuxt/rspack-builder📦@nuxt/rspack-builderReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Nuxt is an open-source web development framework for Vue.js. In @nuxt/rspack-builder and @nuxt/webpack-builder from versions 3.15.4 to before 3.21.7 and 4.0.0 to before 4.4.7, there is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still be stolen during dev when using the webpack / rspack builder if the dev server is bound to a non-loopback address (e.g. nuxt dev --host) and the developer opens a malicious site on the same network. This issue has been patched in versions 3.21.7 and 4.4.7.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @nuxt/webpack-builder | ≥ 4.0.0&&< 4.4.7 | 4.4.7 |
| 📦npm | @nuxt/webpack-builder | ≥ 3.15.4&&< 3.21.7 | 3.21.7 |
| 📦npm | @nuxt/rspack-builder | ≥ 4.0.0&&< 4.4.7 | 4.4.7 |
| 📦npm | @nuxt/rspack-builder | ≥ 3.15.4&&< 3.21.7 | 3.21.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @nuxt/webpack-builder. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @nuxt/webpack-builder to 4.4.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49993 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-49993 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-49993. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-49993 in your dependencies?
O3 detects CVE-2026-49993 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.