{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "4.9.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1c80b668aa6d853f470319eec10a3f61e78a70e6"
            },
            {
              "fixed": "b4aa5380c50ad59a80d1dfdbc229590a4e0133a3"
            }
          ],
          "repo": "https://github.com/amannn/next-intl",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-8f24-v5vv-gm5j"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-601"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40299.json"
  },
  "details": "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`.",
  "id": "CVE-2026-40299",
  "modified": "2026-07-15T01:49:14.611595882Z",
  "published": "2026-04-17T20:49:05.642Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/amannn/next-intl/releases/tag/v4.9.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40299.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/amannn/next-intl/security/advisories/GHSA-8f24-v5vv-gm5j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40299"
    },
    {
      "type": "FIX",
      "url": "https://github.com/amannn/next-intl/commit/1c80b668aa6d853f470319eec10a3f61e78a70e6"
    },
    {
      "type": "FIX",
      "url": "https://github.com/amannn/next-intl/pull/2304"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "next-intl has an open redirect vulnerability"
}