CVE-2026-40299
Severity CVSS v4.0:
MEDIUM
Type:
CWE-601
URL Redirection to Untrusted Site ('Open Redirect')
Publication date:
17/04/2026
Last modified:
29/04/2026
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`.
Impact
Base Score 4.0
6.90
Severity 4.0
MEDIUM