next-intl has an open redirect vulnerability_CVE-2026-40299

6.9 / 10

MEDIUM

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

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 `[email protected]`.

Basic Information

ID CVE-2026-40299

Source GitHub_M

Published Apr 17, 2026 at 20:49

Affected Product

Vendor amannn

Product next-intl

Version < 4.9.1

Affected Versions amannn next-intl < 4.9.1

CWE Classification

CWE-601

References

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    "published": "2026-04-17T20:49:05.642Z",
    "modified": "2026-04-17T20:49:05.642Z",
    "type": "cve",
    "title": "next-intl has an open redirect vulnerability",
    "source": "GitHub_M",
    "references": "https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5j\nhttps://github.com/amannn/next-intl/pull/2304\nhttps://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6\nhttps://github.com/amannn/next-intl/releases/tag/v4.9.1",
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