CVE-2026-40299
Low
Low
Medium
High
Critical
CVSS Score
Vulnerability 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`.
References & Resources
-
https://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6security-advisories@github.com
-
https://github.com/amannn/next-intl/pull/2304security-advisories@github.com
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https://github.com/amannn/next-intl/releases/tag/v4.9.1security-advisories@github.com
-
https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5jsecurity-advisories@github.com
Severity Details
out of 10.0
Low
Weakness Type (CWE)
CWE-601
URL Redirection to Untrusted Site ('Open Redirect')
- Description
- The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
- Exploit Likelihood
- Low
- Typical Severity
- High
- Abstraction Level
- Base
Key Information
- Published Date
- April 17, 2026
