CVE-2026-56390

{
  "id": "CVE-2026-56390",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-29T11:16:49.910",
  "lastModified": "2026-10-23T23:10:00.157",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "GNU Bison improperly handles grammar‑defined output paths. Grammar directives such as %output and %header allow specifying file paths, which are accepted without restriction and override caller‑supplied output options. \nWhen processing attacker-supplied grammar, this behavior allows directing generated files to arbitrary writable locations on the filesystem, potentially overwriting existing files accessible to the Bison process.\n\nMaintainers of this project were notified about this vulnerability, and fixed the issue in commit 8d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable."
    },
    {
      "lang": "es",
      "value": "GNU Bison maneja incorrectamente las rutas de salida definidas por la gramática. Las directivas de gramática como %output y %header permiten especificar rutas de archivo, las cuales son aceptadas sin restricción y anulan las opciones de salida proporcionadas por el llamador.\nAl procesar gramática proporcionada por el atacante, este comportamiento permite dirigir los archivos generados a ubicaciones arbitrarias con permisos de escritura en el sistema de archivos, sobrescribiendo potencialmente archivos existentes accesibles para el proceso de Bison.\n\nLos mantenedores de este proyecto fueron notificados sobre esta vulnerabilidad y corrigieron el problema en el commit 8d101c19d4d9aaedf83a448c925513742d4efcf0. Sin embargo, no proporcionaron un rango de versiones vulnerables. La versión 3.8.2 fue probada y confirmada como vulnerable, otras versiones no fueron probadas pero también podrían ser vulnerables."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "GNU",
          "product": "Bison",
          "defaultStatus": "unknown",
          "repo": "https://cgit.git.savannah.gnu.org/cgit/bison.git/",
          "versions": [
            {
              "version": "3.8.2",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/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:X",
          "baseScore": 4.6,
          "baseSeverity": "MEDIUM",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "userInteraction": "ACTIVE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "LOW",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "CHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 4.0
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-29T12:14:42.510020Z",
          "id": "CVE-2026-56390",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-73"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:gnu:bison:3.8.2:*:*:*:*:*:*:*",
              "matchCriteriaId": "524B249F-965A-4AA8-9F93-54298A0F69FB"
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  ],
  "references": [
    {
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389",
      "source": "[email protected]",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/",
      "source": "[email protected]",
      "tags": [
        "Product"
      ]
    },
    {
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=8d101c19d4d9aaedf83a448c925513742d4efcf0",
      "source": "[email protected]",
      "tags": [
        "Patch"
      ]
    }
  ]
}