ubuntu-cve-2020-24240
Vulnerability from osv_ubuntu
Published
2020-08-25 14:15
Modified
2026-04-22 07:39
Summary
Details

GNU Bison before 3.7.1 has a use-after-free in _obstack_free in lib/obstack.c (called from gram_lex) when a '\0' byte is encountered. NOTE: there is a risk only if Bison is used with untrusted input, and the observed bug happens to cause unsafe behavior with a specific compiler/architecture. The bug report was intended to show that a crash may occur in Bison itself, not that a crash may occur in code that is generated by Bison.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
low
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"
      ]
    }
  ],
  "aliases": [],
  "details": "GNU Bison before 3.7.1 has a use-after-free in _obstack_free in lib/obstack.c (called from gram_lex) when a \u0027\\0\u0027 byte is encountered. NOTE: there is a risk only if Bison is used with untrusted input, and the observed bug happens to cause unsafe behavior with a specific compiler/architecture. The bug report was intended to show that a crash may occur in Bison itself, not that a crash may occur in code that is generated by Bison.",
  "id": "UBUNTU-CVE-2020-24240",
  "modified": "2026-04-22T07:39:30Z",
  "published": "2020-08-25T14:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-24240"
    },
    {
      "type": "REPORT",
      "url": "https://lists.gnu.org/r/bug-bison/2020-07/msg00051.html"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-24240"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-24240"
  ]
}



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