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CVE-2026-86219

Estado: AplazadaCrítica (9.8)—

Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified nonce in server_step.

server_start generates a fresh nonce and sends it in the challenge, and nothing later compares that value against the nonce the client returns. server_step derives the expected digest from the client's own parameters, so a response verifies whenever its digest matches the nonce it carries. The count table it also checks is keyed on the client-supplied nonce and starts empty in each new server object, so a captured first response, carrying `nc=00000001`, passes that too. RFC 2831 defines the nonce in the response as the value the server sent in the preceding challenge.

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An attacker who observes one successful `qop=auth` exchange can replay the captured response against a later session for the same service, host, realm and user, and authenticate as that user without knowing the password.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad de validación de nonce débil en autenticación SASL que permite suplantación de usuarios sin contraseña. AV:N/PR:N/UI:N acceso remoto sin privilegios. Replay de respuestas capturadas autentica al usuario legítimo.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account ManagementMulti-factor AuthenticationVulnerability ScanningUser TrainingPrivileged Process IntegrityPassword Policies

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Authen Sasl Perl — Digest MD5AI

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-86219",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-86219",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-08T18:54:38.530817Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "repo": "https://github.com/perl-authen-sasl/perl-authen-sasl",
          "modules": [
            "Authen::SASL::Perl::DIGEST_MD5"
          ],
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "2.2100",
              "versionType": "custom"
            }
          ],
          "packageURL": "pkg:cpan/Authen-SASL",
          "packageName": "Authen-SASL",
          "programFiles": [
            "lib/Authen/SASL/Perl/DIGEST_MD5.pm"
          ],
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Authen::SASL::Perl::DIGEST_MD5::server_step"
            },
            {
              "name": "Authen::SASL::Perl::DIGEST_MD5::server_start"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-09-06T18:17:23.027",
  "references": [
    {
      "url": "https://datatracker.ietf.org/doc/html/rfc2831#section-2.1.2",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://github.com/perl-authen-sasl/perl-authen-sasl/commit/94337367030612842924f697cead29964a96448d.patch",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/EHUELS/Authen-SASL-2.2000/source/lib/Authen/SASL/Perl/DIGEST_MD5.pm#L203-222",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/EHUELS/Authen-SASL-2.2000/source/lib/Authen/SASL/Perl/DIGEST_MD5.pm#L410-414",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/EHUELS/Authen-SASL-2.2100/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-40918",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "description": [
        {
          "lang": "en",
          "value": "CWE-294"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified nonce in server_step.\n\nserver_start generates a fresh nonce and sends it in the challenge, and nothing later compares that value against the nonce the client returns. server_step derives the expected digest from the client's own parameters, so a response verifies whenever its digest matches the nonce it carries. The count table it also checks is keyed on the client-supplied nonce and starts empty in each new server object, so a captured first response, carrying `nc=00000001`, passes that too. RFC 2831 defines the nonce in the response as the value the server sent in the preceding challenge.\n\nAn attacker who observes one successful `qop=auth` exchange can replay the captured response against a later session for the same service, host, realm and user, and authenticate as that user without knowing the password."
    }
  ],
  "lastModified": "2026-09-08T19:20:10.770",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
}