CVE-2026-46342
Fix: nuxt/nuxt#35077CVE-2026-46342 is a Cross-site Scripting (XSS) vulnerability in nuxt. O3 Security confirms whether CVE-2026-46342 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Nuxt: `__nuxt_island` endpoint does not bind responses to request props, enabling shared-cache poisoning
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-46342.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
nuxtnpm@nuxt/nitro-servernpmDescription
Nuxt is an open-source web development framework for Vue.js. In Nuxt versions 3.1.0 to before 3.21.6 and 4.0.0-alpha.1 to before 4.4.6 and @nuxt/nitro-server versions 3.20.0 to before 3.21.6 and 4.0.0-alpha.1 to before 4.4.6, the /__nuxt_island/* endpoint accepts attacker-controlled props query/body parameters and renders any island component without verifying that the URL-resident hash (<Name>_<hashId>.json) was actually issued for those inputs by <NuxtIsland>. The hash is computed and embedded client-side but never validated server-side, so the same path can return materially different responses depending on the query. This issue has been patched in versions 3.21.6 and 4.4.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nuxt | ≥ 3.1.0&&< 3.21.6 | 3.21.6 |
| 📦npm | nuxt | ≥ 4.0.0-alpha.1&&< 4.4.6 | 4.4.6 |
| 📦npm | @nuxt/nitro-server | ≥ 3.20.0&&< 3.21.6 | 3.21.6 |
| 📦npm | @nuxt/nitro-server | ≥ 4.2.0&&< 4.4.6 | 4.4.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nuxt. 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 to 3.21.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-46342 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-2026-46342 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-2026-46342. 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-2026-46342 in your dependencies?
O3 detects CVE-2026-46342 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.