GHSA-8f24-v5vv-gm5j
next-intl has an open redirect vulnerability
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### 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]`](https://github.com/amannn/next-intl/releases/tag/v4.9.1).
### Credits
Many thanks to [Joni Liljeblad](https://github.com/joniumGit) from [Oura](https://ouraring.com) for responsibly disclosing the vulnerability and for suggesting the fix.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5j
- https://nvd.nist.gov/vuln/detail/CVE-2026-40299
- https://github.com/amannn/next-intl/pull/2304
- https://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6
- https://github.com/amannn/next-intl
- https://github.com/amannn/next-intl/releases/tag/v4.9.1