ubuntu-cve-2026-33250
Vulnerability from osv_ubuntu
Published
2026-03-24 00:16
Modified
2026-05-20 15:27
Summary
Details

Freeciv21 is a free open source, turn-based, empire-building strategy game. Versions prior to 3.1.1 crash with a stack overflow when receiving specially-crafted packets. A remote attacker can use this to take down any public server. A malicious server can use this to crash the game on the player's machine. Authentication is not needed and, by default, logs do not contain any useful information. All users should upgrade to Freeciv21 version 3.1.1. Running the server behind a firewall can help mitigate the issue for non-public servers. For local games, Freeciv21 restricts connections to the current user and is therefore not affected.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-client-gtk",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "2.5.3-1"
          },
          {
            "binary_name": "freeciv-sound-standard",
            "binary_version": "2.5.3-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@2.5.3-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.5.1-1",
        "2.5.2-1",
        "2.5.3-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-client-gtk",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "2.5.10-1"
          },
          {
            "binary_name": "freeciv-sound-standard",
            "binary_version": "2.5.10-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@2.5.10-1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.5.9-1",
        "2.5.10-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-client-gtk",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "2.6.2-1"
          },
          {
            "binary_name": "freeciv-sound-standard",
            "binary_version": "2.6.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@2.6.2-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.6.0-3",
        "2.6.0-4",
        "2.6.1-1",
        "2.6.2-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-client-gtk",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "2.6.6-1"
          },
          {
            "binary_name": "freeciv-sound-standard",
            "binary_version": "2.6.6-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@2.6.6-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.6.3-1",
        "2.6.5-1",
        "2.6.6-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-ruleset-tools",
            "binary_version": "3.1.0+ds-1build5"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "3.1.0+ds-1build5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@3.1.0+ds-1build5?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.0.8-1",
        "3.0.8-2",
        "3.0.8-2build1",
        "3.1.0+ds-1build3",
        "3.1.0+ds-1build4",
        "3.1.0+ds-1build5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-client-gtk4",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-ruleset-tools",
            "binary_version": "3.2.0+ds-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "3.2.0+ds-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@3.2.0+ds-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.4+ds-2",
        "3.2.0+ds-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "freeciv",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-client-extras",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-client-gtk3",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-client-gtk4",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-client-qt",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-client-sdl",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-data",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-ruleset-tools",
            "binary_version": "3.2.4+ds-1"
          },
          {
            "binary_name": "freeciv-server",
            "binary_version": "3.2.4+ds-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "freeciv",
        "purl": "pkg:deb/ubuntu/freeciv@3.2.4+ds-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2.0+ds-1",
        "3.2.1+ds-1",
        "3.2.1+ds-1build1",
        "3.2.2+ds-1",
        "3.2.4+ds-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Freeciv21 is a free open source, turn-based, empire-building strategy game. Versions prior to 3.1.1 crash with a stack overflow when receiving specially-crafted packets. A remote attacker can use this to take down any public server. A malicious server can use this to crash the game on the player\u0027s machine. Authentication is not needed and, by default, logs do not contain any useful information. All users should upgrade to Freeciv21 version 3.1.1. Running the server behind a firewall can help mitigate the issue for non-public servers. For local games, Freeciv21 restricts connections to the current user and is therefore not affected.",
  "id": "UBUNTU-CVE-2026-33250",
  "modified": "2026-05-20T15:27:21Z",
  "published": "2026-03-24T00:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-33250"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-33250"
    },
    {
      "type": "REPORT",
      "url": "https://redmine.freeciv.org/issues/1955"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/longturn/freeciv21/commit/ad8e18ca22595529599782b2984bf44df8d69ed6"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/longturn/freeciv21/releases/tag/v3.1.1"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/longturn/freeciv21/security/advisories/GHSA-f76g-6w3f-f6r3"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-33250"
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.