Buffer overflow in Longturn Freeciv21

CVE-2026-33250

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.012 (67.7th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-33250: held from 0.008 to 0.012.

EPSS over last 30 days · oldest: 0.008 · newest: 0.012 · change: +0.004

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-33250?
CVE-2026-33250 is a high-severity vulnerability in Longturn Freeciv21, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2026-03-24.
How severe is CVE-2026-33250?
High severity. CVSS v3 base score is 7.5 out of 10.