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.
Advisories
Source ID Title
Debian DSA Debian DSA DSA-6173-1 freeciv security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 24 Mar 2026 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Longturn
Longturn freeciv21
Vendors & Products Longturn
Longturn freeciv21

Tue, 24 Mar 2026 02:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Crash when receiving specially-crafted packets
Weaknesses CWE-121
CWE-20
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-23T23:38:02.070Z

Reserved: 2026-03-18T02:42:27.509Z

Link: CVE-2026-33250

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-24T00:16:29.830

Modified: 2026-03-24T00:16:29.830

Link: CVE-2026-33250

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-24T10:29:50Z

Weaknesses