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CVE-2026-34872

Estado: AnalizadaCrítica (9.1)—

An issue was discovered in Mbed TLS 3.5.x and 3.6.x through 3.6.5 and TF-PSA-Crypto 1.0. There is a lack of contributory behavior in FFDH due to improper input validation. Using finite-field Diffie-Hellman, the other party can force the shared secret into a small set of values (lack of contributory behavior). This is a problem for protocols that depend on contributory behavior (which is not the case for TLS). The attack can be carried by the peer, or depending on the protocol by an active network attacker (person in the middle).

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 en FFDH sin validación de entrada (CWE-347) en librerías criptográficas accesibles por red; atacante remoto puede manipular el secreto compartido. La falta de comportamiento contributivo permite ataque de intermediario, impactando autenticación (T1553) y derivación de claves (T1187).

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 ManagementFilter Network TrafficVulnerability ScanningRestrict Registry PermissionsPassword PoliciesOperating System Configuration

Tecnologías afectadas (2)

ARM — Mbed TLSARM — Tf-psa-crypto

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-34872",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-34872",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-04-01T19:51:10.004400Z"
        }
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    "cvssMetricV31": [
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        "type": "Secondary",
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.2,
        "exploitabilityScore": 3.9
      }
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  },
  "affected": [
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      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
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      ]
    }
  ],
  "published": "2026-04-01T20:16:27.493",
  "references": [
    {
      "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-ffdh-peerkey-checks/",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
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      "source": "cve@mitre.org"
    }
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      "value": "An issue was discovered in Mbed TLS 3.5.x and 3.6.x through 3.6.5 and TF-PSA-Crypto 1.0. There is a lack of contributory behavior in FFDH due to improper input validation. Using finite-field Diffie-Hellman, the other party can force the shared secret into a small set of values (lack of contributory behavior). This is a problem for protocols that depend on contributory behavior (which is not the case for TLS). The attack can be carried by the peer, or depending on the protocol by an active network attacker (person in the middle)."
    }
  ],
  "lastModified": "2026-06-17T10:39:46.057",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
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              "versionEndExcluding": "3.6.6"
            },
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              "vulnerable": true,
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          ],
          "operator": "OR"
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  "sourceIdentifier": "cve@mitre.org"
}