What’s Vulnerable › Vulnerabilities

CVE-2020-5209: NetHack command line parsing of options starting with -de and -i is subject to a buffer overflow

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-01-28 · updated 2026-06-17
• Weakness: CWE-120

Description

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: before 3.6.5 — fixed in 3.6.5

How to fix

Upgrade to a fixed version: NetHack 3.6.5. Check the vendor advisory for mitigations.

References

• https://github.com/NetHack/NetHack/commit/f3def5c0b999478da2d0a8f0b6a7c370a2065f77
• https://github.com/NetHack/NetHack/security/advisories/GHSA-fw72-r8xm-45p8
• https://github.com/NetHack/NetHack/commit/f3def5c0b999478da2d0a8f0b6a7c370a2065f77
• https://github.com/NetHack/NetHack/security/advisories/GHSA-fw72-r8xm-45p8

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