GitHub Advisoryadvisory · npm
GHSA-8f24-v5vv-gm5j next-intl has an open redirect vulnerability
MEDIUM
Official page ↗
- Aliases
- CVE-2026-40299
- Ecosystem
- npm
- Packages
- next-intl
- Severity
- Moderate
- CVSS 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
- Weaknesses
- CWE-601
- Reviewed
- 2026-04-10
Affected packages
• npm next-intl: < 4.9.1 → fixed in 4.9.1
Description
Impact
Applications using the `next-intl` middleware with `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.
Patches
The problem has been patched, please update to `[email protected]`.
Credits
Many thanks to Joni Liljeblad from Oura for responsibly disclosing the vulnerability and for suggesting the fix.
Related
Alias · CVE (1)
- CVE-2026-40299 next-intl provides internationalization for Next.js. vulnerability
Weakness · CWE (1)
- CWE-601 URL Redirection to Untrusted Site weakness
References
- https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5j web
- https://nvd.nist.gov/vuln/detail/CVE-2026-40299 advisory
- https://github.com/amannn/next-intl/pull/2304 web
- https://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6 web
- https://github.com/amannn/next-intl package
- https://github.com/amannn/next-intl/releases/tag/v4.9.1 web