CVE-2026-84292: Fast uri Fast-uri Vulnerable To Authority Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qw65-cvwx-89v3",
  "modified" : "2026-09-28T21:24:39Z",
  "published" : "2026-09-28T21:24:39Z",
  "aliases" : [ "CVE-2026-84292" ],
  "summary" : "fast-uri vulnerable to authority injection via an unvalidated port in serialize",
  "details" : "### Impact\n\n`fast-uri` serializes the `port` component of a URI without validating it. When recomposing the authority, `fast-uri` escapes the userinfo and host components but concatenates the port verbatim, so a `port` value that is not a sequence of digits can inject authority delimiters. For example, serializing a component whose `port` is `@127.0.0.1:8124` produces `http://trusted.example:@127.0.0.1:8124/app`, demoting the intended host to userinfo and pointing the authority at an attacker-controlled host. Both `fast-uri` and Node's `URL` read the result back as the attacker's host with no error, so re-validating the built URI does not catch it.\n\nThis affects applications that build URIs from parts and assign untrusted data to the `port` component (for example a fixed host from configuration and a port taken from user input or a service record). The same path is reachable through `serialize()`, `normalize()`, and `equal()` in their object forms. A `port` obtained from `parse()` is always digits and is not affected.\n\n### Patches\n\nThis vulnerability has been patched in fast-uri `4.1.4`, `3.1.7`, and `2.4.6`. `recomposeAuthority` now rejects any port that is not `*DIGIT` per RFC 3986. All users should upgrade.\n\n### Workarounds\n\nIf upgrading is not immediately possible, validate the `port` value against the RFC 3986 grammar (digits only) before passing a component to `serialize()`, `normalize()`, or `equal()`, and reject anything else, for example `if (!/^\\d*$/.test(String(port))) throw new Error('invalid port')`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "fast-uri"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.4.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "fast-uri"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "3.1.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "fast-uri"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.1.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fast-uri/security/advisories/GHSA-qw65-cvwx-89v3"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-84292"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fast-uri/commit/820e8478dd7da3d09f187bfaf35d50b71f67b8b4"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/fastify/fast-uri"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fast-uri/releases/tag/v2.4.6"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fast-uri/releases/tag/v3.1.7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/fast-uri/releases/tag/v4.1.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-116" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-28T21:24:39Z",
    "nvd_published_at" : "2026-09-02T20:17:39Z"
  }
}