Freeciv21 · Freeciv21 · CVE-2026-33250
**Name of the Vulnerable Software and Affected Versions**
Freeciv21 versions prior to 3.1.1
**Description**
Freeciv21, a free and open-source turn-based strategy game, is susceptible to a crash caused by a stack overflow when processing specially crafted network packets. This issue allows a remote attacker to disrupt public servers, and a malicious server can crash the game on a player’s machine. The vulnerability does not require authentication. Logs, by default, do not provide helpful information for investigation.
**Recommendations**
Upgrade to Freeciv21 version 3.1.1.
For non-public servers, running the server behind a firewall can help mitigate the issue.
For local games, Freeciv21 restricts connections to the current user and is therefore not affected.