CVE-2026-44372: Nitro open redirect via protocol-relative URL bypass in wildcard rules

CVE-2026-44372 · Severity: medium · CVSS 6.1 · Published 2026-05-13

Nitro, a web server framework, contains a vulnerability that allows attackers to redirect users from a legitimate website to a malicious one. By manipulating a specific type of web address rule, an attacker can trick the server into sending users to an external site while the initial link appears to belong to the trusted domain. This can be used in phishing attacks to steal user credentials or distribute malware.

Technologies: UnJS NitroPack. Vendors: npm, UnJS.

Quick answers

Is CVE-2026-44372 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-44372 being exploited in the wild.
How severe is CVE-2026-44372?
Medium severity, with a CVSS score of 6.1, published 13 May 2026.
Which products and versions are affected?
nitro (npm) SEMVER:introduced=0,fixed=3.0.260429-beta; nitropack (npm) SEMVER:introduced=0,fixed=2.13.4; UnJS Nitro < 3.0.260429-beta; UnJS NitroPack < 2.13.4.
Is there a fix for CVE-2026-44372?
Yes. nitro (npm): upgrade to 3.0.260429-beta or later; nitropack (npm): upgrade to 2.13.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-44372 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-44372?
Check whether you run nitro (npm), nitropack (npm), UnJS Nitro or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • nitro (npm): upgrade to 3.0.260429-beta or later
    npm install nitro@3.0.260429-beta
  • nitropack (npm): upgrade to 2.13.4 or later
    npm install nitropack@2.13.4

Technical details

An open redirect vulnerability exists in Nitro's 'routeRules' when using wildcard suffixes (e.g., '/**'). The vulnerability is caused by improper handling of leading slashes in the matched pathname. When an attacker provides a path with an extra slash (e.g., '/legacy//evil.com'), Nitro's runtime strips the prefix but preserves the double slash, resulting in a protocol-relative URL (//evil.com). Browsers resolve this as a redirect to an external host. This affects deployments using the Nitro runtime but excludes those handled at the CDN layer (like Vercel or Cloudflare Pages). The fix involves updating the 'ufo' dependency to 1.6.4+ and patching the Nitro runtime to collapse leading slashes.

Affected products

  • unjs nitro < 3.0.260429-beta
  • unjs nitropack < 2.13.4

Identifiers

  • CVE-2026-44372
  • GHSA-9phm-9p8f-hw5m

Timeline

  • 2026-04-29: patched: Initial patch released in beta and stable branches
  • 2026-05-06: disclosed: GitHub Advisory published
  • 2026-05-13: advisory: NVD published CVE-2026-44372

References

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