CVE-2026-47269

{
  "id": "CVE-2026-47269",
  "sourceIdentifier": "[email protected]",
  "published": "2026-05-27T21:16:18.810",
  "lastModified": "2026-10-26T12:10:00.130",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0,  pam_usb's deny_remote feature checks utmpx ut_addr_v6 to detect whether an authentication request originates from a remote session. The outer guard was if (utent->ut_addr_v6[0] != 0), which only tests the first 32-bit word of the 128-bit address field. IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) store the IPv4 address in ut_addr_v6[3] with ut_addr_v6[0] == 0. On systems where the SSH daemon listens on :: (IPv6 wildcard) with AddressFamily any -- common on Ubuntu and Debian -- incoming IPv4 connections are recorded in utmpx as IPv4-mapped IPv6 addresses. The outer check evaluates to false, the remote-detection block is skipped entirely, and the session is treated as local. deny_remote=true does not block the authentication. An attacker with physical access to a registered USB device can authenticate over SSH on an affected system as if they were sitting at a local terminal, bypassing the deny_remote restriction. This vulnerability is fixed in 0.9.0."
    },
    {
      "lang": "es",
      "value": "pam_usb proporciona autenticación de hardware para Linux utilizando medios extraíbles ordinarios. Antes de la versión 0.9.0, la característica deny_remote de pam_usb verifica utmpx ut_addr_v6 para detectar si una solicitud de autenticación se origina de una sesión remota. La protección externa era if (utent  ->  ut_addr_v6[0] != 0), que solo prueba la primera palabra de 32 bits del campo de dirección de 128 bits. Las direcciones IPv6 mapeadas a IPv4 (::ffff:x.x.x.x) almacenan la dirección IPv4 en ut_addr_v6[3] con ut_addr_v6[0] == 0. En sistemas donde el demonio SSH escucha en :: (comodín IPv6) con AddressFamily any -- común en Ubuntu y Debian -- las conexiones IPv4 entrantes se registran en utmpx como direcciones IPv6 mapeadas a IPv4. La verificación externa se evalúa como falsa, el bloque de detección remota se omite por completo y la sesión se trata como local. deny_remote=true no bloquea la autenticación. Un atacante con acceso físico a un dispositivo USB registrado puede autenticarse a través de SSH en un sistema afectado como si estuviera sentado en un terminal local, eludiendo la restricción deny_remote. Esta vulnerabilidad se corrige en la versión 0.9.0."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "mcdope",
          "product": "pam_usb",
          "versions": [
            {
              "version": "< 0.9.0",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.2
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-05-28T12:50:16.970323Z",
          "id": "CVE-2026-47269",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-284"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d8be05fd015e36abc3c7d94e5",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/mcdope/pam_usb/security/advisories/GHSA-jmmj-qhrq-w45g",
      "source": "[email protected]"
    }
  ]
}