ubuntu-cve-2026-56390
Vulnerability from osv_ubuntu
Published
2026-07-30 00:00
Modified
2026-07-30 00:00
Summary
Details

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. When 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. Maintainers 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.

Severity
4.6 (Medium)
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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.0.4.dfsg-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.0.4.dfsg-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.0.2.dfsg-2",
        "2:3.0.4.dfsg-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.0.4.dfsg-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.0.4.dfsg-1build1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.0.4.dfsg-1build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.5.1+dfsg-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.5.1+dfsg-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.4.1+dfsg-4",
        "2:3.4.2+dfsg-1",
        "2:3.5.1+dfsg-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.7.6+dfsg-1build1",
        "2:3.8.2+dfsg-1",
        "2:3.8.2+dfsg-1build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.8.2+dfsg-1build1",
        "2:3.8.2+dfsg-1build2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "bison",
            "binary_version": "2:3.8.2+dfsg-1build4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "bison",
        "purl": "pkg:deb/ubuntu/bison@2:3.8.2+dfsg-1build4?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:3.8.2+dfsg-1build3",
        "2:3.8.2+dfsg-1build4"
      ]
    }
  ],
  "aliases": [],
  "details": "GNU Bison improperly handles grammar\u2011defined output paths. Grammar directives such as %output and %header allow specifying file paths, which are accepted without restriction and override caller\u2011supplied output options. When 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. Maintainers of this project were notified about this vulnerability, and fixed the issue in commit\u00a08d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested\u00a0and confirmed as vulnerable, other versions were not tested but might also be vulnerable.",
  "id": "UBUNTU-CVE-2026-56390",
  "modified": "2026-07-30T00:00:00Z",
  "published": "2026-07-30T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-56390"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-56390"
    },
    {
      "type": "REPORT",
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389/"
    },
    {
      "type": "REPORT",
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=8d101c19d4d9aaedf83a448c925513742d4efcf0"
    },
    {
      "type": "REPORT",
      "url": "https://cert.pl/en/posts/2026/07/CVE-2026-56389"
    },
    {
      "type": "REPORT",
      "url": "https://cgit.git.savannah.gnu.org/cgit/bison.git/"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-56390"
  ]
}



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