Home

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`.

PUBLISHED Reserved 2026-04-10 | Published 2026-04-17 | Updated 2026-04-20 | Assigner GitHub_M




MEDIUM: 6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

Product status

< 4.9.1
affected

References

github.com/...t-intl/security/advisories/GHSA-8f24-v5vv-gm5j

github.com/amannn/next-intl/pull/2304

github.com/...ommit/1c80b668aa6d853f470319eec10a3f61e78a70e6

github.com/amannn/next-intl/releases/tag/v4.9.1

cve.org (CVE-2026-40299)

nvd.nist.gov (CVE-2026-40299)

Download JSON