CVE-2024-34343 — nuxt
MEDIUMCVE-2024-34343 is a medium-severity (CVSS 6.3) Cross-site Scripting (XSS) vulnerability in nuxt. 1 public exploit reference exists, so weaponization risk is real. A fix is available for nuxt — see the affected versions and patch details below.
Cross-site Scripting (XSS) in navigateTo if used after SSR in nuxt
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-34343.
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.
How urgent is this, really
CVE-2024-34343 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
nuxtnpmDescription
Summary
The navigateTo function attempts to blockthe javascript: protocol, but does not correctly use API's provided by unjs/ufo. This library also contains parsing discrepancies.
Details
The function first tests to see if the specified URL has a protocol. This uses the unjs/ufo package for URL parsing. This function works effectively, and returns true for a javascript: protocol.
After this, the URL is parsed using the parseURL function. This function will refuse to parse poorly formatted URLs. Parsing javascript:alert(1) returns null/"" for all values.
Next, the protocol of the URL is then checked using the isScriptProtocol function. This function simply checks the input against a list of protocols, and does not perform any parsing.
The combination of refusing to parse poorly formatted URLs, and not performing additional parsing means that script checks fail as no protocol can be found. Even if a protocol was identified, whitespace is not stripped in the parseURL implementation, bypassing the isScriptProtocol checks.
Certain special protocols are identified at the top of parseURL. Inserting a newline or tab into this sequence will block the special protocol check, and bypass the latter checks.
PoC
POC - https://stackblitz.com/edit/nuxt-xss-navigateto?file=app.vue
Attempt payload X, then attempt payload Y.
Impact
XSS, access to cookies, make requests on user's behalf.
Recommendations
As always with these bugs, the URL constructor provided by the browser is always the safest method of parsing a URL.
Given the cross-platform requirements of nuxt/ufo a more appropriate solution is to make parsing consistent between functions, and to adapt parsing to be more consistent with the WHATWG URL specification.
Note
I've reported this vulnerability here as it is unclear if this is a bug in ufo or a misuse of the ufo library.
This ONLY has impact after SSR has occurred, the javascript: protocol within a location header does not trigger XSS.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nuxt | all versions | 3.12.4npm install nuxt@3.12.4 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nuxt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nuxt to 3.12.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-34343 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-34343 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-34343. 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-2024-34343 in your dependencies?
O3 Security finds CVE-2024-34343 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.