CVE-2026-40299
next-intl provides internationalization for Next.js.
Published Apr 17, 2026 · updated Jun 17, 2026
next-intl provides internationalization for Next.js. Applications using the middleware prior to version 4.9.1with 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 .
Code
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Timeline
Detection, updates, and resolution for this record.
Apr 17, 2026 · NIST NVD
Detected
next-intl provides internationalization for Next.js. Applications using the middleware prior to version 4.9.1with 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 trus
Jun 17, 2026 · NIST NVD
Updated
next-intl provides internationalization for Next.js. Applications using the middleware prior to version 4.9.1with 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 trus
Sources
- CVE.orgVulnerability recordCVE-2026-40299
Official CVE identifier
cve.org - NIST NVDVulnerability recordCVE-2026-40299
next-intl provides internationalization for Next.js. Applications using the middleware prior to version 4.9.1with could construct URLs where path handling and the WHATWG URL parser resolved a relative redirect target to another host (e.g. s
nvd.nist.gov