CVE-2020-5209: Nethack

High severity, CVSS 7.8. EPSS: 0.8% chance of exploitation in the next 30 days.

In NetHack before 3.6.5, unknown options starting with -de and -i can cause a buffer overflow resulting in a crash or remote code execution/privilege escalation. This vulnerability affects systems that have NetHack installed suid/sgid and shared systems that allow users to influence command line options. Users should upgrade to NetHack 3.6.5.

Affected products

• Nethack Nethack: before 3.6.5 (fixed in 3.6.5)

Published 2020-01-28. Last modified 2026-06-17.