CVE-2026-40299CWE-601

next-intl has an open redirect vulnerability

Medium · published April 17, 2026

CVSS v4.0
6.9
EPSS
1%
Percentile
44.6
In the wild
Unconfirmed
What it is

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 `[email protected]`.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
EPSS
0.00540 · 44.6th percentile
Weakness
CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')
Published
2026-04-17T20:49Z
EPSS history
Timeline
  • 17 APR 20:49Z
    next-intl has an open redirect vulnerability
    cvelistv5