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)
EPSS: 0.008 (53.6th percentile) — read the EPSS interpretation.
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.
Affected products
- Longturn Freeciv21 — versions < 3.1.1
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
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.