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Nuxt: Reflected XSS in `navigateTo()` external redirect

Moderate severity GitHub Reviewed Published May 18, 2026 in nuxt/nuxt • Updated May 19, 2026

Package

npm nuxt (npm)

Affected versions

>= 3.4.3, <= 3.21.5
>= 4.0.0-alpha.1, <= 4.4.5

Patched versions

3.21.6
4.4.6

Description

Summary

navigateTo() with external: true generates a server-side HTML redirect body containing a <meta http-equiv="refresh"> tag. The destination URL is only sanitized by replacing " with %22, leaving <, >, &, and ' unencoded. An attacker who can influence the URL passed to navigateTo(url, { external: true }) can break out of the content="…" attribute and inject arbitrary HTML/JavaScript that executes under the application's origin.

This is a different root cause from CVE-2024-34343 (GHSA-vf6r-87q4-2vjf), which addressed javascript: protocol bypass. The issue here is triggered by any valid URL containing >.

Impact

Applications that pass user-controlled input to navigateTo(url, { external: true }) — typically via a ?next= / ?redirect= query parameter used for post-login or "return to" flows — are vulnerable to reflected cross-site scripting. The injected script runs in the context of the application's origin during the server-rendered redirect response, before the meta-refresh fires.

Details

In packages/nuxt/src/app/composables/router.ts, the SSR redirect path builds an HTML response body with only " percent-encoded in the destination URL:

const encodedLoc = location.replace(/"/g, '%22')
nuxtApp.ssrContext!['~renderResponse'] = {
status: sanitizeStatusCode(options?.redirectCode || 302, 302),
body: `<!DOCTYPE html><html><head><meta http-equiv="refresh" content="0; url=${encodedLoc}"></head></html>`,
headers: { location: encodeURL(location, isExternalHost) },
}

The Location header is normalised through encodeURL() (which uses the URL constructor and correctly percent-encodes attribute-significant characters). The HTML body uses a narrower sanitiser. That mismatch is the root cause.

Proof of concept

Global middleware that forwards a query parameter to navigateTo:

// middleware/redirect.global.ts
export default defineNuxtRouteMiddleware((to) => {
const next = to.query.next as string | undefined
if (next) {
 return navigateTo(next, { external: true })
}
})

Request:

GET /?next=https://evil.example/x><img src=x onerror=alert(document.domain)>

Response body:

<!DOCTYPE html><html><head><meta http-equiv="refresh" content="0; url=https://evil.example/x><img src=x onerror=alert(document.domain)>"></head></html>

The > after evil.example/x terminates the content="…" attribute, and the <img onerror> tag executes JavaScript in the application's origin before any redirect
occurs.

Patches

Fixed in nuxt@4.4.6 and nuxt@3.21.6 by #35052. The fix percent-encodes the full set of HTML-attribute-significant characters (&, ", ', <, >) before interpolating the URL into the meta-refresh body

Workarounds

If you can't upgrade immediately, validate user-controlled URLs before passing them to navigateTo(url, { external: true }). At minimum, normalise through new URL(input).toString() and reject inputs containing < or > (a normalised URL with these characters is malformed and safe to refuse).

References

@danielroe danielroe published to nuxt/nuxt May 18, 2026
Published to the GitHub Advisory Database May 19, 2026
Reviewed May 19, 2026
Last updated May 19, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality Low
Integrity Low
Availability None
Subsequent System Impact Metrics
Confidentiality Low
Integrity Low
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

EPSS score

Weaknesses

Improper Neutralization of Script in Attributes in a Web Page

The product does not neutralize or incorrectly neutralizes javascript: or other URIs from dangerous attributes within tags, such as onmouseover, onload, onerror, or style. Learn more on MITRE.

CVE ID

CVE-2026-45669

GHSA ID

GHSA-fx6j-w5w5-h468

Source code

Credits

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