CVE-2026-27855

{
  "id": "CVE-2026-27855",
  "sourceIdentifier": "[email protected]",
  "published": "2026-03-27T09:16:19.610",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and username is altered in passdb, then OTP credentials can be cached so that same OTP reply is valid. An attacker able to observe an OTP exchange is able to log in as the user. If authentication happens over unsecure connection, switch to SCRAM protocol. Alternatively ensure the communcations are secured, and if possible switch to OAUTH2 or SCRAM. No publicly available exploits are known."
    },
    {
      "lang": "es",
      "value": "La autenticación OTP de Dovecot es vulnerable a ataques de repetición bajo condiciones específicas. Si la caché de autenticación está habilitada y el nombre de usuario se altera en passdb, entonces las credenciales OTP pueden ser almacenadas en caché de modo que la misma respuesta OTP sea válida. Un atacante capaz de observar un intercambio OTP puede iniciar sesión como el usuario. Si la autenticación ocurre a través de una conexión no segura, cambie al protocolo SCRAM. Alternativamente, asegure que las comunicaciones estén protegidas y, si es posible, cambie a OAUTH2 o SCRAM. No se conocen exploits disponibles públicamente."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Open-Xchange GmbH",
          "product": "OX Dovecot Pro",
          "defaultStatus": "unaffected",
          "modules": [
            "core"
          ],
          "versions": [
            {
              "version": "0",
              "lessThanOrEqual": "2.3.0",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
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      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N",
          "baseScore": 6.8,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 5.2
      },
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
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          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
        },
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        "impactScore": 3.6
      }
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    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-03-27T19:39:33.275509Z",
          "id": "CVE-2026-27855",
          "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-294"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
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          "cpeMatch": [
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              "vulnerable": true,
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  "references": [
    {
      "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}