Vulnerability · Published Apr 17, 2026 · Assigned by GitHub_M

CVE-2026-40299next-intl has an open redirect vulnerability

Medium 6.9

In plain English

A medium-severity open redirect in next-intl from amannn. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.3%top 72.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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`.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	next-intl	4.9.1	GHSA-8f24-v5vv-gm5j

Affected products (as reported)

Vendor	Product	Versions
amannn	next-intl	< 4.9.1

Weakness: CWE-601 · 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

References

https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5j x_refsource_CONFIRM
https://github.com/amannn/next-intl/pull/2304 x_refsource_MISC
https://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6 x_refsource_MISC
https://github.com/amannn/next-intl/releases/tag/v4.9.1 x_refsource_MISC