# CVE-2026-40299

> Vulnerability.

## Description

next-intl provides internationalization for Next.js. Applications using the `next-intl` middleware prior to version 4.9.1with `localePrefix: 'as-needed'` could construct URLs where path handling and the WHATWG URL parser resolved a relative redirect target to another host (e.g. scheme-relative `//` or control characters stripped by the URL parser), so the middleware could redirect the browser off-site while the user still started from a trusted app URL. The problem has been patchedin `next-intl@4.9.1`.

## Key facts

- **CVE ID:** CVE-2026-40299
- **Published:** 2026-04-17
- **CWE codes:** CWE-601

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40299

## Citation

> AI Analytics. CVE-2026-40299. Retrieved 2026-07-12 from https://api.ai-analytics.org/cve/CVE-2026-40299. Derived from NIST NVD. Licensed CC0.

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