GHSA-Q3J6-QGPJ-74H6

Vulnerability from github – Published: 2026-05-08 17:15 – Updated: 2026-05-08 17:15
VLAI
Summary
fast-uri vulnerable to path traversal via percent-encoded dot segments
Details

Impact

fast-uri v3.1.0 and earlier decodes percent-encoded path separators (%2F) and dot segments (%2E) before applying dot-segment removal in normalize() and equal(). This makes encoded path data behave like real / and .., so distinct URIs collapse onto the same normalized path.

For example, http://example.com/public/%2e%2e/admin normalizes to http://example.com/admin, and equal() considers them the same URI.

Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed. A path that looks confined under an allowed prefix can normalize to a different location.

Patches

Upgrade to fast-uri >= 3.1.1.

Workarounds

None. Upgrade to the patched version.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.0"
      },
      "package": {
        "ecosystem": "npm",
        "name": "fast-uri"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-6321"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T17:15:09Z",
    "nvd_published_at": "2026-05-04T20:16:20Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\n`fast-uri` v3.1.0 and earlier decodes percent-encoded path separators (`%2F`) and dot segments (`%2E`) before applying dot-segment removal in `normalize()` and `equal()`. This makes encoded path data behave like real `/` and `..`, so distinct URIs collapse onto the same normalized path.\n\nFor example, `http://example.com/public/%2e%2e/admin` normalizes to `http://example.com/admin`, and `equal()` considers them the same URI.\n\nApplications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed. A path that looks confined under an allowed prefix can normalize to a different location.\n\n### Patches\n\nUpgrade to `fast-uri` \u003e= 3.1.1.\n\n### Workarounds\n\nNone. Upgrade to the patched version.",
  "id": "GHSA-q3j6-qgpj-74h6",
  "modified": "2026-05-08T17:15:09Z",
  "published": "2026-05-08T17:15:09Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/security/advisories/GHSA-q3j6-qgpj-74h6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6321"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fastify/fast-uri"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fast-uri vulnerable to path traversal via percent-encoded dot segments"
}


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