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CVE-2026-12803

Estado: AnalizadaAlta (8.7)—

In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery). This issue also affects Bouncy Castle for Java LTS before 2.73.12.

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.

AEAD forgery por nonce no vinculado permite manipular mensajes cifrados (VI:H). Acceso red sin autenticación (AV:N/PR:N). Impacto: integridad comprometida de datos en tránsito.

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

Vulnerability ScanningRestrict File and Directory PermissionsPrivileged Account ManagementRemote Data StorageNetwork SegmentationLimit Access to Resource Over Network

Tecnologías afectadas (2)

Bouncycastle — Bc-javaBouncycastle — Bouncy Castle FOR Java LTS

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-12803",
  "cveTags": [],
  "metrics": {
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      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-12803",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-08-03T15:22:13.635738Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
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          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 8.7,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "AMBER",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
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  },
  "affected": [
    {
      "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
      "affectedData": [
        {
          "repo": "https://github.com/bcgit/bc-java",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "modules": [
            "core"
          ],
          "product": "BC-JAVA",
          "versions": [
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              "status": "affected",
              "version": "0",
              "lessThan": "1.85",
              "versionType": "maven"
            }
          ],
          "platforms": [
            "all"
          ],
          "packageURL": "pkg:maven/org.bouncycastle/bcprov-jdk18on",
          "packageName": "bcprov",
          "programFiles": [
            "KCCMBlockCipher"
          ],
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://github.com/bcgit/bc-lts-java",
          "vendor": "Legion of the Bouncy Castle Inc.",
          "modules": [
            "core"
          ],
          "product": "BC-LTS-JAVA",
          "versions": [
            {
              "status": "affected",
              "version": "2.73.0",
              "lessThan": "2.73.12",
              "versionType": "maven"
            }
          ],
          "platforms": [
            "all"
          ],
          "packageURL": "pkg:maven/org.bouncycastle/bcprov-lts8on",
          "packageName": "bcprov-lts8on",
          "programFiles": [
            "KCCMBlockCipher"
          ],
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/",
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-08-03T04:16:39.177",
  "references": [
    {
      "url": "https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af",
      "tags": [
        "Patch"
      ],
      "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
    },
    {
      "url": "https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc",
      "tags": [
        "Patch"
      ],
      "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
    },
    {
      "url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012803",
      "tags": [
        "Third Party Advisory",
        "Patch"
      ],
      "source": "91579145-5d7b-4cc5-b925-a0262ff19630"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "91579145-5d7b-4cc5-b925-a0262ff19630",
      "description": [
        {
          "lang": "en",
          "value": "CWE-354"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery). This issue also affects Bouncy Castle for Java LTS before 2.73.12."
    }
  ],
  "lastModified": "2026-09-02T14:37:53.583",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "FA6A5663-2E62-44AA-8A64-A3CB0DC8813B",
              "versionEndExcluding": "1.85"
            },
            {
              "criteria": "cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "F5ED4F42-08FF-4642-815D-1ED0C82FDBD2",
              "versionEndIncluding": "2.73.11"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "91579145-5d7b-4cc5-b925-a0262ff19630"
}