SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney

{
  "id": "0cf540ab5e5822dabe90c9f6cec6fe1c4f4a4391ade3ffee290cf6fa8aecfb9f",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-115700",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney",
    "summary": "Interpretation Conflict vulnerability in hackney_url in benoitc hackney allows Server Side Request Forgery via a percent-encoded bracketed IPv6 literal or an IP literal with a trailing dot. A host such as %5B%3A%3Affff%3A127%2E0%2E0%2E1%5D (decoding to [::ffff:127.0.0.1]) or 127.0.0.1. is not an IP address to a caller's allowlist built on uri_string:parse/1 and inet:parse_address/1, while hackney connects to the address it denotes. The same applies to a Location target when redirects are followed. The IP-literal gate that hackney_url:normalize/2 applies to a percent-decoded host, added to close the percent-encoded IP bypass of CVE-2026-47076, passes the decoded value to inet_parse:address/1 as is. The connect path in hackney_happy:parse_address/1 drops a surrounding bracket pair, and the resolver ignores a trailing dot, so both forms pass the gate and still reach the literal address. Domain names with a trailing dot and unencoded IPv6 literals are not affected. This issue affects hackney: from 4.0.1 before 4.9.0.",
    "evidence": "cve:CVE-2026-115700",
    "products": [
      {
        "name": {
          "value": "hackney",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "hackney",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-115700",
      "aliases": [
        "CVE-2026-115700"
      ],
      "metrics": [
        {
          "format": "CVSS",
          "cvssV4_0": {
            "Safety": "NOT_DEFINED",
            "version": "4.0",
            "Recovery": "NOT_DEFINED",
            "baseScore": 6.9,
            "Automatable": "NOT_DEFINED",
            "attackVector": "LOCAL",
            "baseSeverity": "MEDIUM",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N",
            "providerUrgency": "NOT_DEFINED",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "privilegesRequired": "NONE",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "HIGH",
            "vulnConfidentialityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "affected": [
        {
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "modules": [
            "hackney_url"
          ],
          "product": "hackney",
          "versions": [
            {
              "status": "affected",
              "version": "4.0.1",
              "lessThan": "4.9.0",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:hex/hackney",
          "packageName": "hackney",
          "programFiles": [
            "src/hackney_url.erl"
          ],
          "collectionURL": "https://repo.hex.pm",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "hackney_url:normalize/2"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "modules": [
            "hackney_url"
          ],
          "product": "hackney",
          "versions": [
            {
              "status": "affected",
              "version": "452620a92ec1da2e6b4862a049a2a4f04b42068f",
              "lessThan": "f19561a0b422376348c91537e51377ab7325f4ee",
              "versionType": "git"
            }
          ],
          "packageURL": "pkg:github/benoitc/hackney",
          "packageName": "benoitc/hackney",
          "programFiles": [
            "src/hackney_url.erl"
          ],
          "collectionURL": "https://github.com",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "hackney_url:normalize/2"
            }
          ]
        }
      ],
      "modified": "2026-10-26T13:49:02.744Z",
      "provider": "cve",
      "references": [
        "https://github.com/benoitc/hackney/releases/tag/4.9.0",
        "https://cna.erlef.org/cves/CVE-2026-115700.html",
        "https://osv.dev/vulnerability/EEF-CVE-2026-115700",
        "https://github.com/benoitc/hackney/pull/987",
        "https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f",
        "https://github.com/benoitc/hackney/commit/f19561a0b422376348c91537e51377ab7325f4ee"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
          "shortName": "EEF",
          "dateUpdated": "2026-10-26T13:49:02.744Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-115700",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 307256,
  "published_at": "2026-10-26T13:49:02.744+00:00"
}