FKIE_CVE-2026-42770

Vulnerability from fkie_nvd - Published: 2026-06-09 17:17 - Updated: 2026-07-23 08:10
Severity
3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Summary
Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the peer key is not properly checked for the subgroup membership. Impact summary: A malicious peer which presents an X9.42 key carrying the victim's p and g parameters, a forged q = r (a small prime factor of the cofactor (p−1)/q_local), and a public value Y of order r can recover the victim's private key after a small number of key exchange attempts. When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the subgroup membership check Y^q ≡ 1 (mod p) is performed using the peer's own q parameter, not the local key's q. The peer's domain parameters are then matched against the domain parameters of the private key, but the value of q is not compared. A malicious peer who presents an X9.42 key carrying the victim's p, g, a forged q = r (a small prime factor of the cofactor), and a public value Y of order r passes all checks. The shared secret then takes only r distinct values, leaking priv mod r. Repeating for each small-prime factor of the cofactor and combining via CRT recovers the full private key (Lim–Lee / small-subgroup-confinement attack). The realistic attack surface is narrow: principally CMP deployments with long-lived RA/CA DHX keys and bespoke enterprise or government applications using X9.42 DHX static keys with interactive protocols and therefore this issue was assigned Low severity. The FIPS modules in 4.0, 3.6, 3.5, 3.4, 3.1.2 and 3.0 are affected by this issue.
References
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/3da5a516cd2635a320ff748503db2cef7c4b0f02Patch
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/3ddbb7ab50bd93dfc59cbe08e269a67605aeebdbPatch
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/5f452bba2c681423d8fcffd120a19b757ee42e3cPatch
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/7fbfde7677ed8808828bf00ff01c937ca04bdda2Patch
openssl-security@openssl.orghttps://github.com/openssl/openssl/commit/ca2237ab5615641b662183b077f62c08d75e8070Patch
openssl-security@openssl.orghttps://openssl-library.org/news/secadv/20260609.txtVendor Advisory
Impacted products
Vendor Product Version
openssl openssl *
openssl openssl *
openssl openssl *
openssl openssl *
openssl openssl 4.0.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "OpenSSL",
          "vendor": "OpenSSL",
          "versions": [
            {
              "lessThan": "4.0.1",
              "status": "affected",
              "version": "4.0.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.6.3",
              "status": "affected",
              "version": "3.6.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.5.7",
              "status": "affected",
              "version": "3.5.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.4.6",
              "status": "affected",
              "version": "3.4.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.0.21",
              "status": "affected",
              "version": "3.0.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "openssl-security@openssl.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "EDB88756-EDFE-4886-A267-3F19342A6042",
              "versionEndExcluding": "3.0.21",
              "versionStartIncluding": "3.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "BF7E21E7-AEC0-4882-B1F1-2D056B506F22",
              "versionEndExcluding": "3.4.6",
              "versionStartIncluding": "3.4.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "6B6B9930-C549-4D88-9784-AF32CCDDB87A",
              "versionEndExcluding": "3.5.7",
              "versionStartIncluding": "3.5.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "D41B3C45-EC73-4DC8-989D-B2E2792E102F",
              "versionEndExcluding": "3.6.3",
              "versionStartIncluding": "3.6.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*",
              "matchCriteriaId": "6E881B9A-1A0A-4BC0-8160-20C00561167D",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42)\npeer key, the peer key is not properly checked for the subgroup membership.\n\nImpact summary: A malicious peer which presents an X9.42 key carrying the\nvictim\u0027s p and g parameters, a forged q = r (a small prime factor of the\ncofactor (p\u22121)/q_local), and a public value Y of order r can recover the\nvictim\u0027s private key after a small number of key exchange attempts.\n\nWhen EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the\nsubgroup membership check Y^q \u2261 1 (mod p) is performed using the peer\u0027s\nown q parameter, not the local key\u0027s q. The peer\u0027s domain parameters are\nthen matched against the domain parameters of the private key, but the value\nof q is not compared.\n\nA malicious peer who presents an X9.42 key carrying the victim\u0027s p, g,\na forged q = r (a small prime factor of the cofactor), and a public\nvalue Y of order r passes all checks. The shared secret then takes only\nr distinct values, leaking priv mod r. Repeating for each small-prime\nfactor of the cofactor and combining via CRT recovers the full private\nkey (Lim\u2013Lee / small-subgroup-confinement attack).\n\nThe realistic attack surface is narrow: principally CMP deployments with\nlong-lived RA/CA DHX keys and bespoke enterprise or government applications\nusing X9.42 DHX static keys with interactive protocols and therefore this\nissue was assigned Low severity.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, 3.1.2 and 3.0 are affected by this\nissue."
    },
    {
      "lang": "es",
      "value": "Resumen del problema: Cuando se llama a EVP_PKEY_derive_set_peer() con una clave de par DHX (X9.42), la clave de par no se verifica correctamente para la pertenencia al subgrupo.\n\nResumen del impacto: Un par malicioso que presenta una clave X9.42 que contiene los par\u00e1metros p y g de la v\u00edctima, una q forjada = r (un peque\u00f1o factor primo del cofactor (p?1)/q_local), y un valor p\u00fablico Y de orden r puede recuperar la clave privada de la v\u00edctima despu\u00e9s de un peque\u00f1o n\u00famero de intentos de intercambio de claves.\n\nCuando se llama a EVP_PKEY_derive_set_peer() con una clave de par DHX (X9.42), la verificaci\u00f3n de pertenencia al subgrupo Y^q ? 1 (mod p) se realiza utilizando el propio par\u00e1metro q del par, no la q de la clave local. Los par\u00e1metros de dominio del par se comparan entonces con los par\u00e1metros de dominio de la clave privada, pero el valor de q no se compara.\n\nUn par malicioso que presenta una clave X9.42 que contiene la p, g de la v\u00edctima, una q forjada = r (un peque\u00f1o factor primo del cofactor), y un valor p\u00fablico Y de orden r pasa todas las verificaciones. El secreto compartido toma entonces solo r valores distintos, filtrando priv mod r. Repitiendo para cada factor primo peque\u00f1o del cofactor y combinando mediante CRT se recupera la clave privada completa (ataque Lim-Lee / de confinamiento de subgrupo peque\u00f1o).\n\nLa superficie de ataque realista es estrecha: principalmente despliegues de CMP con claves DHX de RA/CA de larga duraci\u00f3n y aplicaciones empresariales o gubernamentales a medida que utilizan claves est\u00e1ticas DHX X9.42 con protocolos interactivos y, por lo tanto, a este problema se le asign\u00f3 una severidad Baja.\n\nLos m\u00f3dulos FIPS en 4.0, 3.6, 3.5, 3.4 y 3.0 se ven afectados por este problema."
    }
  ],
  "id": "CVE-2026-42770",
  "lastModified": "2026-07-23T08:10:00.137",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-42770",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-09T19:34:57.693097Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-09T17:17:08.523",
  "references": [
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/openssl/openssl/commit/3da5a516cd2635a320ff748503db2cef7c4b0f02"
    },
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/openssl/openssl/commit/3ddbb7ab50bd93dfc59cbe08e269a67605aeebdb"
    },
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/openssl/openssl/commit/5f452bba2c681423d8fcffd120a19b757ee42e3c"
    },
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/openssl/openssl/commit/7fbfde7677ed8808828bf00ff01c937ca04bdda2"
    },
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/openssl/openssl/commit/ca2237ab5615641b662183b077f62c08d75e8070"
    },
    {
      "source": "openssl-security@openssl.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://openssl-library.org/news/secadv/20260609.txt"
    }
  ],
  "sourceIdentifier": "openssl-security@openssl.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-325"
        }
      ],
      "source": "openssl-security@openssl.org",
      "type": "Secondary"
    }
  ]
}



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