CVE-2026-44372
ADVISORY - githubSummary
A redirect route rule like:
routeRules: {
"/legacy/**": { redirect: "/**" }
}
is intended to rewrite paths within the same host. Before the patch, an attacker could turn the rewrite into a cross-host redirect by sliding an extra slash in after the rule prefix. Example exploit:
GET /legacy//evil.com
Nitro stripped /legacy from the matched pathname and joined the remainder against the rule's target. The remainder was //evil.com, which the join preserved verbatim, so Nitro responded with Location: //evil.com. Browsers resolve //evil.com as a protocol-relative URL against the current scheme, sending the user to https://evil.com.
Are you affected?
Users may be affected if all of the following are true:
- Their project uses Nitro's
routeRuleswith aredirectentry. - The target uses a
/**wildcard suffix to forward sub-paths (e.g.redirect: "/**",redirect: "/new/**",proxy: { to: "http://upstream/**" }). - The
redirectrule is not handled natively at the CDN layer. Thevercel,netlify,cloudflare-pages, andedgeonepresets translaterouteRules.redirectinto platform config (vercel.json,_redirects, EdgeOne v3 config) and serve the redirect at the edge — those deployments bypass the Nitro runtime entirely and are not affected. Every other preset executes the redirect through the Nitro runtime and can be vulnerable.
Impact
Open redirect from any host serving Nitro with a wildcard redirect rule. The redirect target is fully attacker-controlled, the URL looks legitimate (it starts with the victim's domain), and the browser silently follows it.
Patched versions
Upgrade to one of:
- 2.13.4 or later (or upgrade lockfile with latest ufo 1.6.4+)
- 3.0.260429-beta or later (https://github.com/nitrojs/nitro/pull/4236)
The fix has two parts:
ufois bumped to^1.6.4(unjs/ufo@5cd9e67), which collapses any run of leading slashes to a single/insidewithoutBase. This covers the typical"/scope/**"rule.- The Nitro runtime additionally collapses leading
//before joining when the rule path itself is/**(in rare case which casewithoutBaseis never called and the raw pathname flows straight intojoinURL("", …)).
Common Weakness Enumeration (CWE)
URL Redirection to Untrusted Site ('Open Redirect')
URL Redirection to Untrusted Site ('Open Redirect')
GitHub
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CVSS SCORE
5.3medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| nitropack | npm | - | - | <2.13.4 | 2.13.4 |
| nitro | npm | - | - | <3.0.260429-beta | 3.0.260429-beta |
CVSS:4 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker's payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system. Examples include: utilizing a website that has been modified to display malicious content when the page is rendered (most stored XSS or CSRF) running an application that calls a malicious binary that has been planted on the system using an application which generates traffic over an untrusted or compromised network (vulnerabilities requiring an on-path attacker).
There is no loss of confidentiality within the Vulnerable System.
There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Subsequent System.
There is no loss of integrity within the Vulnerable System.
Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Subsequent System.
There is no impact to availability within the Vulnerable System.
There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
NIST
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